"A Woody", I think no chance for a sailboat rental but likely you already have a good boat for that lake. Both Sumner and I have old Mac classics and these end up being good sailboats for overnighting on Lake Powell because they have completely retracting centerboard and rudders. I have not spent any water time on the far west end of the lake but the more Eastern part of the lake that Ive been on (from about Rainbow Bridge to Hite) typically has steep drop offs from almost all beach's - like over 100 feet deep 20 foot from the beach. So you cant do traditional anchoring. Every time you find a new camp, its a little engineering feat but I generally look for some place up in the canyons that has some sort of accessible and interesting beach and some of the bushes growing near the beach. I retract the centerboard and rudder and "jury rig" some sort of tie up to rocks, bushes, logs, etc. Often in the summer, house boats already have the "easy" camp sites. Out of the 20 nights Ive spent there, every camp was somehow different and the tie up was different. Having water ballast is also a plus, a couple of times, Ive camped somewhat over sand bars (not by choice) and keep an "air mattress" manual pump in the boat in case I get stuck from either water level changing (some times of the year, I think near 1 inch over night can happen) or because of the wash of a big house boat going by. I haven't had to use it yet but he hand pump is to dump some water ballast in case you did get stuck.
We've gone there the last four years (always to Bullfrog since were coming from Denver) and its been just a great family vacation.
Some pictures from this years trip here
http://analogengineering.com/sail/powell/powell2010.html
Older pictures from the last four years and some links
http://analogengineering.com/sail/powell/
I wouldn't go there expecting good sailing.. however, you can still get in some very nice days sailing but they are only a bonus to better reasons for going there.