I yak-packed Powell in fall 2013. It motivated me to buy a motorboat (something I never thought I would do in my life). Here's a link to that TR:
http://backcountrypost.com/threads/kayaking-lake-powell-moqui-canyon.2485/
But with that said it was still awesome. It was just a lot tougher and more dangerous than I expected it to be. My impression is that you are biting way more off than you should trying to yak it from Antelope all the way to Wetherill and back. The real benefit of a yak on Lake Powell is getting into the nooks and crannies that the motorboats don't. Nowadays I motorboat in and bring inflatable yaks to get into the narrow stuff.
The main channel sucks for kayaks. Like
super sucks.
@Aldaron tells me that this isn't the case over Thanksgiving, but that's also a pretty chilly time to be paddling, IMO. May can be really hit and miss weather wise. Depending on the time of month and the weather that year, you'll probably be looking at water temps in the 60's. Still pretty cold for lots of swimming unless the sun is beating down and the wind is calm. And then the wind. Now that's the real problem in the spring. It is notoriously windy out there that time of year. In a kayak, that can be a serious problem. Big open bays make big ass white caps. And to complicate thing, there are so may areas without a useable shoreline. It's not quite as bad on the south end, but you'll go for miles without any place to get out of the water if you needed to. It's kind of like being in open ocean because if you tip over, you're hosed. That vertical sandstone wall next to you isn't going to be much help in the 400-foot deep water. You also have tour boats down that way which put off enough wake to scare the crap out of a motor boater. But May is a little lighter in traffic, so that's on your side. Definitely picking up though.
If I were you, I'd set my sights closer to
Labyrinth and Face Canyons (
or even West). You have way more than enough to keep you entertained and challenged exploring up that far. Trying to smash it out all the way to Wetherill and back in that time could be really tough and would require excellent conditions. All are great slots that you can hike into and lots of rolling slick rock to explore. I frequently see shuttle companies picking up/dropping off kayakers near the mouth of Labyrinth for multi-day trips.
Keep in mind that the still water, wind and boat wakes make your mileage a lot tougher. It looks like over 12 miles just to the mouth of Labyrinth. I bet that would take you most of a day. You'd be well over 30 miles of paddling to get to the mouth of Wetherill, one-way!
As for a shitter, wag bags with something air tight to put them in is what you'll need to be legal. A piece of 6"(?) ABS pipe with sealed twist off ends is a good DIY solution for a groover. Just make it bigger than you think you'll need. Those bags don't pack down all that well and the smell is still horrendous. I read in another TR that Canyonlands was possibly allowing them to be in a regular dry bag. Your dry bag will be tainted for life though.
As for the yak, I'd be afraid to do it in a sit-on-top, but maybe yours is more stable than mine was.
My buddy has a little 3 legged stool chair that he takes in his kayak. I'm not sure what brand it is. I think chairs without backs are pointless. Kayaks make decent chairs too.
Hope that all makes sense. I've been up for like 36 hours straight.
