Nimbostratus
MVPit is part of it, combined with a configuration partition you are closer. then you isolate your config and routing. although you can still borrow from the main configuration partition and if you want to from main routing domain.
if you want more isolation from each other you can look at vCMP, then you have virtual instances of BIG-IP on one box. but that goes beyond ACE contexts.
in general it might be wise to contact your local F5 partner, they might have done some more ACE to F5 migrations and can possibly help.