"Am I right to think that by July 25 mosquitos won't be much of a problem. I hear there's so little water this year that they came early/will leave early."
We keep reciting that same prediction about mosquitos in hopes that it may be true.
So far, I have kept to the slightly drier places, and bugs are present, but they sure are not nearly as bad as they have been in the past. I'm still scratching at the bites from July 5-7.
About the only thing that you can predict with certainty is that the wet stream crossings will be far easier than they were last year at this time.
As for the tarp, you might practice setting your stakes when the ground is a solid slab of granite. You might be able to tie guylines to big rocks sitting around, but you may need extra cord length for that.