You don't need an iPad, get any Verizon tablet. Look into a used ellipsis 7. You can suspend a line for up to 3 months at a time & 6 months per year, but this also pushes off your upgrade date for as long as you suspend it.
ETA: I'm pretty sure you only need 1 tablet. You should even be able to borrow one from somebody for a few minutes, you just need a different SIM card for each number.