I think a bivy would be just fine in your case. Cost may be a factor, but I would look at any bivy made out of eVent. They are waterproof (not just resistant) and breathable to the point that I have never had condensation in my (two). Integral designs makes some of the best. Add a 9x7 silnylon or spinaker tarp. Some weigh as little as 7 oz (see Mountain Laurel Designs). Add a removable bug net to the tarp (about 3-4 oz. See Gossamer Gear). For around 16-24 ounces you will have a very versatile shelter with these benefits:

-ultimate flexibility with this type of modular system.
-superier weather proofing. Note: Silnylon is not waterproof. Anything over 1-1.5 psi of moisture will mist through. The eVent will keep you very protected.
-warmer for the weight. A good bivy will minimize heat loss due to convection (i.e. the wind stealing preacious body heat), something that I suspect you will face in Alaska.
-Bug netting that hangs from the inside of a tarp is optional. In situations (i.e. no bugs and protected), just roll out the bivy and hop in.
-Tarp - if reasonably large will give you more 'move around' room than an ultralight tent. It will also permit multiple pitching options (i.e. food prep area, cooking area, sun or rain protection at mid day without having to take off your boots, etc). It will also afford room to change clothes, do a dance, act as a huge vestibule, whatever.

In any event, there are a lot of choices and bivy + tarp works, as do tarptents, freestanding framed tents, etc. Really it is a matter of finding out what will work for you and I believe a bivy + tarp (you would not need it at alpine levels but should take one in all others) would work for you.