You have some cool ideas. When I looked at my Jansport, I could see better what you were talking about. Some advantages I see w/ your option 2:
1. Automatically waterproof. Don’t have to mess with ponchos, garbage sacks, pack covers, Ziplocs, etc.,
2. external frames just plane breath better.

I have two external frames--- a Coleman and this Jansport (which is lighter). I like external frames when I need to be a sherpa for my family.

-Barry