BTW, I noticed above the mention of crabro. I've had both chipokae and crabro before but never in the same tank. IME, crabros are pretty darn feisty. Do you think the crabro would back down to the chipokae?
I only ask because it sounds like a crabro is the one more wanted and I'm afraid if the crabro doesn't back down the chipokae would kill it and I'd feel bad suggesting one.
IMO Crabro get a bad rap - they are not even close to Chipokae when it comes to aggression, more like Lombardoi - just one of the more aggressive common species (when i say common - i mean readily available )
Every Crabro i have kept, male and female, have been somewhere in the middle order of the tank hierarchy, if not lower. I have yet to see this famed aggression in many years of keeping them. My current female is the wimp of the tank, although she is in with all males
Did i mention - i like them.