Step 1. make sure you have no orders (if you have order waiting you must buy it or wait for next RL day if it is overriding something you want to keep)
Step 2. close game, go to data, copy save to usb (and keep usb in the wii u otherwise the next steps will mess up)
Step 3. set timezone in your settings to the earliest possible.
Step 4. load up splatoon and order ONE GEAR that has at least a double what you want.
Step 5, close splatoon, set timezone to the highest you can go (hopefully you live in a place where this gap is big enough in time)
Step 6. open splatoon and buy the gear
step 7. repeat step 3-6 till you find a double of something.
Step 8. Once you find a double of something close your game, set timezone to earliest, and do game HD (wii U) >usb override.
Step 9. order the gear you found a double on (reason for step 8 is so you get your money back +gear you actually want to keep since you are only looking for double/triple and reject results may be worse then what you have)
Step 10. once ordered, close game, set timezone to latest
Step 11, close game, now do USB> HD (wii u) override.
step 12. buy the gear you got a double on, snail it, and play rank to get the 3rd slot.
Step 13 a, congratulations, you got triple gear without spending much or depending on luck
step 13 b, if you get anything but a matching sub, quit game, do HD (wii u)> usb override.
Step 14. repeat step 12 till you get step 13a result.
13a looks like this: