My boys were all housed together until very recently. Jekyll and Hyde are pretty old now (27 months), and Jekyll has developed a URI he can't seem to shake, despite being on doxy and bronchodilator. Richelieu has wanted to be the alpha for ages, so when Jekyll (the previous alpha) gets sick, Squish bothers him like crazy. I didn't want all that stress for Jekyll-belly, so I put him and Hyde in the bottom half of my cage (it's a Ferplast Furet Tower) and the three younger boys in the top. It seems to be a good arrangment for now, and they all get cuddled and free-ranged together at night. :)
Aw, I do hope your guy gets better soon! It's sweet they are all getting lots of love, though.
Sansa is sitting on my shoulder as I type this, rooting through my hair. I'd have got rats AGES ago if I'd known they were such darlings!