I would still try to water test it in the garage. You can just bring the tank in there you dont need the whole canopy and stand. I may be a little paranoid but I always get kinda scared when getting a used tank. If you test it now at least if there is god forbid an issue it will leak on concrete and not the carpet. It won't come pouring out like a flood if theres a leak, you'll just have water, not a wave that can destroy the stuff in the garage.
I just go by better safe than sorry.....LOL
I knew that skimmer was expensive, hehe, it just looks like it is. keeping in mind a new skimmer will run over $200 for a good one for your tank you have to determine if you want to buy now or just keep looking.
I might have missed it, but is the tank drilled that you got?