IMHO, If you're going to do it right you really need to use a "Cyclone". Shop vacs don't generate enough pressure and a compressor doesn't supply enough volume. A cyclone - >
Cyclone II Pool Line Blower Vac 3.0hp, 4128100
Yes you can try other means and there are youtube videos out there but there also was the one showing people how to drill into their new i7 phone to reveal the "hidden" ear phone jack !! And some people actually did !!
Clueless iPhone 7 owners tricked into DRILLING hole in their phones to 'get a headphone jack'
Having the right tool is cheap insurance on making sure the water is out and it's about the cost of two paid closings. If you know you'll have the pool for at least two more years it will pay for itself and you'll have the tool too !! Make sure you have good O rings on the plugs.
You have a big pool and I'm guessing the runs are long. I wouldn't trust my pool to a shop vac or compressor and I have a couple of both but I can see -30 here in Wisconsin and the thought of a broken underground pipe scares me greatly. Was going to get one this year but time is running out. I'll have one next year as I'm tired of seeing two guys spend 15 minutes blowing and plugging my lines and getting a 115-140 dollar bill a couple weeks later.
Just my two cents.