Welcome to our forum.
Nobody seems to want to actually answer your questions. I'm not a dealer, but if it was me winterizing a spa, I'd either suck every bit of water out of the plumbing as possible or figure out a way to circulate RV antifreeze into the works. Either one would be okay as long as no water was left in the plumbing to freeze.RV antifreeze is very safe, and non toxic. So I'd probably remove as much as possible with a wet vac, fill the spa normally, and power up. The little left in the lines shouldn't hurt anything, and would likely be totally flushed out at the first water change. Not sure if the stuff comes in colorless form- the stuff I use in my boat engine is pink.