Personally, I think you would be better off with a folding chair with a
built in foot rest.
Carrying two stackable chairs will be problematic.
An alternative is to leave the chairs with one of us on this usegroup
that will be camping with our airplanes near the spot you want to watch
the airplanes from. I have already told other friends of mine that they
are welcome to leave their chairs at my airplane while they are walking
around the other parts of the airport. You are welcome to leave them if
I am camped near where you want to watch.