Sorry it's been a while I've been really busy but I thought I'd update y'all.
First I renamed Theo Tuvok because everytime I saw him I thought "Vulcan" (big trekkie here...) and Spock didn't fit so he got Voyager's chief of security.
Any way I've been letting Herby and Tuvok hang out in the morning while I clean their cages for 10-15minutes and they've been fine. Then last night they were able to be out together for a full hour with just a few very small tuffs.
Nothing major and they had a grand time, so did Mom; they're sooo cute!
So things are definitely going up and I hope to be able to extend their time even more though I'm still really wary of putting them together with anything they associate as "personal." One thing I have been doing is having a Mom's Night where I let them out individually and spend all my time focused with just one, each taking a turn, and no together time. Takes longer but I really like it and they do too.