Yeah, this could work as a large map (like Kelp Dome, but with more stuff).
As for my own map ideas, perhaps a map on a train would be nice. Like, a moving train, with 6 cars (the farthest two for the spawn points, the two closer to the center would have a bunch of furniture to use for cover, the center cars would be just floors with crates for climbing and cover). Its cars would be fairly wide, and have kinda-high-ish ceilings, but the two center cars would be just a floor (no walls/ceilings) with boxes to climb up and/or use for cover, letting you more easily access the tops of the cars (there would be small platforms outside the windows, but you would have to ink up the side of the train from there, whereas you could just jump from the boxes to the roofs). You would start inside the cars, but could go outside via the windows and run along the tops of the cars (which you could also ink), which have no cover, so you have to be wary of flanking and ambushes but can hold off oncoming attackers with long-range weapons. The roofs of the two cars between the crates and the spawn points (times like this make me wish I could draw so I could illustrate this somehow) would have grate and non-grated roofs, allowing limited use of Inkstrikes beyond the center without making them useless (though the cars with spawn points would have no grating on their roofs, so you can't Inkstrike the spawn cars). Windows would be placed on both sides of each car, with 1 pair on the spawn-point-cars and 2 pairs on the cars after that (one set near the spawn-point-car and one near the center cars); there are none on the center cars, but those have no walls or roofs anyway. Occasionally, the train would turn to the left or right (I want to say every 30 seconds, but it could be more/less), both shifting the layout a bit (skewing to the left/right, essentially) and making the center car's boxes and whatever furniture is inside the train's cars slide to one side or the other (not necessarily all the way, or even all the furniture), returning to its original position once the turn is completed (I would make this 30 seconds, just to make the changes once per minute each, but it could be more/less as well). Each half of the stage would be a mirror of the other.
For Splat Zones, there would be 2 Zones, and they would be on both of the center cars. I can't think of a better place to put them, and it forces combat to take both Zones (which I think is important for Splat Zones).
For Tower Control, the Tower would start in the exact center of the map and take a kind of S-shaped path through the center before settling on the rooftop of the nearby car (on each side). The Tower's path would shift to the left/right when the train turns (so it would stay the same), but it would mostly go through boxless areas, allowing enemies to attack the Tower from similar or higher elevation to the Tower's platform.
Overall, it's certainly a different sort of map from what we currently have, one that frequently changes and forces you to alter your strategy and forces combat by being fairly linear while still allowing the use of multiple routes via the rooftops.
And here's another one:
Octo Valley, a straightforward map that incorporates several single-player objects.
Both sides start with a tower, with the spawn point for each team at the top. From there, you can leap down to a fairly-wide rectangular platform that slopes downward, except for two plateaus in the middle of the platform on each side that have an Inkrail on them, leading to two tallish side platforms flanking the center one. The Inkrails are each one team's color from the start of the match, and cannot be changed. In the center is a fairly low but very wide platform, with 4 fairly tall circular platforms on the sides (2 on each side, 1 per Inkrail; very close, but you still have to hop to move between them). The exact center of the platform has a Sponge a bit above it, which can be enlarged by firing into it (though you can still walk under it, even at maximum size); if one team has enlarged it, the other can shrink it back down by shooting at it, then grow it in their own color. The Sponge could be used as a vantage point to attack the side platforms, but is also large enough at maximum size to maybe reach the side platforms by jumping from it. The side platforms in the center have non-inkable walls, so you can't climb up them, but there are also small circles of land around them at center-platform-height, letting you go around them to attack the enemy's side of the map or attack enemies in the center from behind.
In Ranked, the Sponge is gone, replaced with a pair of grated platforms bridging the side platforms above the center. Additionally, there are inkable blocks on each side of the center, letting you access the side platforms from the center.
In Splat Zones, there is only 1 Zone, on the center platform. Controlling the grate-bridges is critical, but you mustn't neglect the side platforms either or you'll be flanked and driven away.
In Tower Control, the Tower is shorter than usual, and its path is a straight line, then turns at the end to stop at the right side of the spawn-point-tower. It's a bit like Walleye Warehouse, but even straighter, if that helps visualize it.
Overall, it's a very straightforward map, but I think it could work. The center is the focal point of the map, but the Inkrails can be used to attack enemies trying to encroach on your base up to a certain point (since you can jump off of them to get some extra height, then rain ink down on your foes) as well as providing an alternate route to the center, and the Sponge is useful for keeping a higher vantage point to snipe from, if you can keep enemies away from it. In Ranked, the grate-bridges let you dominate the center if you can control them, but you still have to be alert to avoid getting flanked from the side platforms or from behind (since you can sneak around the side platforms). I'm not sure this one is good, but it might work.
Also,
@gameonion &
@Taiga Kagami that sounds like a great idea too!