Dear fellow Arizonian 4-wheelers

I am planning a vacation this July/August (my stepdaughter is visiting from Russia) and I decided to take a route through Arizona and Utah. My preliminary plan is:

1) July 25 and 26 - camping at Toroweap / Tuweep overlook in Northern Grand Canyon;
2) July 27 and 28 - exploring the north shore of the Lake Powell;
3) July 29, 30, 31, Aug 1 - camping in Goblin Valley State Park and exploring the vicinity, on foot and in the vehicle (I already booked the campsite).

I have a question: how manageable the heat in Northern Grand Canyon this time of the year ? Who has the experience camping near GC and/or Lake Powell in summer ?

I've been several times to Arizona, but all my travels happened in the winter.

Can anybody give me some advises how to spend two days around the Lake Powell ? I was thinking about Alstrom Point, and/or Grand Bench, and/or Hole-in-the-Rock, and/or Bullfrog marina. How is the heat there ? How the lake is accessible for the swimming from those places ? I know that the lake is mostly in Utah, but there is no dedicated Utah section here, and you guys probably is very familiar with Utah.

May be, you can give me advises how to plan these 8 days better.

Thanks a lot in advance !