We do this, and what we do is take cash and go buy them at Target (we get 5% off each card), then pay them off right away before we leave the store. Consider this if you have a Target charge card.
The one thing I would caution is that Disney has been known to be sporadic in when they charge your room charges to your CC on file. It's supposed to be at certain $ thresholds, but reports are that it is very inconsistent. So pay it off every day. Otherwise they might charge your CC when you were planning to use your gift cards.
You can watch the charges that are going on your room account on the MDE app. Just watch it and go by and pay it off before it gets too high. Or to eliminate the possibility of missing the charges going to your CC on file, just use the GC to pay wherever you need it instead of using your Magic Band!
Thanks! I think I'll just use the gc's for what I want them for (specific meals) and use my cc to pay the room charges. Earning points for the next trip, right?!?!?