would this work if i just transfered the water and fish from the 30 gal qt to a 10 temporarily, and then fully clean the 30 gal, make up a whole new batch of hyposalinity water, get all the parameters to match up, and then transfer the fish back to the 30? so they'll basically be in completely new water.
That would work, but in order for TT to be successful (in your case) you'd need to do a total of 5 transfers. Day 1 (for you) would begin the day you put all your fish in that 10 gal. You would then need to transfer them to a new tank on the mornings of Day 4, Day 7, Day 10 and finally Day 13 (done).
It is imperative that the tank and all equipment be thoroughly sanitized in-between transfers. I clean everything in a 10:1 f/w:vinegar solution immediately, and then let it all air dry until the morning I need it. Also, you'll need to keep a close eye on ammonia (but you can use ammonia reducers with TT), and TT is only useful to eradicate Ich - not Velvet. I've never done TT in hypo conditions, but I don't see any reason why you can't.