Also, it is ILLEGAL to use 100LL in roadgoing vehicles.
As for the E0, by definition it is offered only outside urban smog control areas, so you must drive (sometimes quite a distance) to get it.
E0 will store for a long time. (not like E10 which goes bad quickly).
With all the problems you’re having with your engines, it would be well worth it to get a couple 55 gal drums.