Our MS Bands have been rehearsing with 8' spacing front to back and 6' side-to-side since we came back fully at the end of the second six-weeks. There are definitely some phasing issues we've encountered, but we've been able to work through them with our groups I think. We postponed our Winter concert until the 18th of this next month - see how that goes! (Outdoors under an old roof of an elementary cafeteria that the rest was knocked out but left as a pavilion)
As far as UIL? I think in our school we'll be able to get our groups together if things continue like this fall. We're making some safer rep choices this spring to be safe in case of shutdowns/quarantines though. Given S&E is virtual, I suspect we'll probably have something like that or judges coming to our campuses for UIL. If that's the case then it won't be an issue to deal with different space/setup concerns. I can't imagine even by April that we can make a regular C&SR contest happen.