and have a disconnect next to the tub (within a few feet), as long as there is nothing else on that circuit?

I have a sub-panel in the basement, which is near the deck where I want to install the tub. I could run 40' of 6/3, from a 50A GFCI breaker in the basement sub panel, out to the deck, then have a fuseless disconnect box where I wire in the tub.

Any problems with this? It still gives a disconnect near the tub, and uses the basement sub panel, which is still pretty near the deck.

Thanks in advance!