Use a standard tub filler, and get a long(er) spout. You can find both single handle and dual handle tub valves. Most of the two handle ones are thermostatically controlled (which I like, but cost more) verses a pressure balanced one. While a 1/2" valve will work, to fill the tub faster (if your supply lines can be 3/4"), go with a 3/4" valve. Expect a 1/2" valve to provide about 6-8 gpm (depending on how hot the WH is set - higher, means mixing more cold, which increases the total volume), while a 3/4" valve can provide over twice that flow (if the pipes are big enough).