I "agree" with only your "Allow anyone from any grand company per side." but they seems that want mantain the GC requirement, so I would like to suggest something like:
If you had enlisted in all the GC (and maybe achieved the horse with all of them), you can take part to FLs as mercenary with lower reward or even whitout reward, JUST FOR FUN.
Even if it will be accessible to a small part of players it will improve a lot queue time :/