I know several folks each year come up here to Alaska for backpacking, pack rafting, fishing, or just as tourists so I'll pass along a helpful tidbit:
The mosquitos are really bad this year.
Yeah, it's Alaska; you expect mosquitos; it's "the State Bird", etc.
But in 15 years, I've never seen it this bad. Homesteaders from the 1940's can remember one other year this bad, but those who arrived 10-20-30 years ago are all agreeing it is as bad as they've seen it.
I live in Kenai, am in Soldotna all the time, and just got back from a family backpacking trip on the Resurrection Trail between Cooper Landing and Seward. It's bad all over.
I PM'ed Dena in Eagle River (north of Anchorage) and she reports likewise. And has heard similar stories from Fairbanks.
I'm not a mosquito weenie. Most summers, I never use any DEET. Either there's wind or I'm moving enough that it isn't worth it. This year, I'm not only using DEET, but they seem to be ignoring the DEET and I'm resorting to long pants and long-sleeve shirts. Further, I have, for first time in many years, dug out the mosquito head nets and was VERY glad we had them along on our BPing trip.
What you should do? I wouldn't cancel your trip, but I'd definitely have loose-fitting long-sleeve, long-legged clothing that is quick-dry (my thin Gramacci pants and a long-sleeve nylon travel shirt (buttons, collar) worked really well. That and the head net had me wishing only for gloves. Really, on a warm summer day, if I had loose fitting, bug-proof gloves, I would have worn them. Oh, and I know a tarp is lighter than a tent, but screw the tarp - bring an fully enclosed tent.
My theory is that last year was so very benign because of deep frost level (cold weather arrived before insulating snow) and very few mosquitos to eat allowed very few dragon flies, crane flies, etc, to survive (dragon larva eat mosquito larva, adult dragonflies eat adult mosquitoes, etc). Now, with almost no predators, this year's crop has free rein.
We now return you to your regularly scheduled trip planning.