What I foresee is that I can get 80 at my home field, but will need to
top off or completely fill up with 100LL as I go along. Is this truly
ok?

Yes.

I'm trying to avoid ever having a stuck exhaust valve again, but the
reality is that 80 is hard to find and autogas is frequently not an
option (depending on the airport).

Build a fuel truck. See mine at
http://www.alexisparkinn.com/fuel_truck.htm .

It's saved me over $3000 in fuel costs, and the plane runs much better, too.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"