We had a large-diameter hose and emptied into the garden - took next to no time with the size hose we had!
We also used drop sheets from the hardware store for underneath the pool, as well as some towels around (that never got wet). I was very still in the water, but DS was getting in and out He didn't even mind the vernix for his last dip!
Waterbirth is far too easy peasy so if you have the inclination, just hire one