I've got a 31C..which holds "8 passengers"....but that doesn't mean it's gonna hold 8 Adults!
Unless you've got a couple of smaller guys in the band, the galley table bed isn't going to be very comfortable...and the other beds are going to have to be shared. If you get the 31J, that would have the two bunks, but still, it's gonna be tight.
Of course, you can have the guys bring air mattresses, and take turns sleeping on the floor, but it's gonna become extremely tight in there.
If you don't need the galley and such, you could work on getting a school or coach conversion (think Partridge Family
) and set up a bunch of bunks in it....with eating in town, or maybe a small fridge or coolers. As it is, the fridge in the 31J will really be a bit small for 8 guys, and it won't keep the beer nearly as cold as you'd like!!
Will the 31J work for you....yes! Will it be comfortable? maybe not, as it's really not set up for 8 people to be riding around in.......think about it, 2 in the cab, 2-3 at the galley table, 3 at the sofa.....but I can tell you, the galley table isn't comfortable....so you'll have guys laying in bed.
Also, the water capacity and drain tanks will be very limited for that size crowd....and I'm guessing that you don't plan to be at campgrounds every night....so you won't have "hook-ups" all the time.
Good luck, you'll need it.......
...there is a reason that you see the huge coaches for bands...and even then, the coach isn't for the entire band....or if it is, it's a 4-5 person band.....
And, this doesn't touch on the extra trailer for the equipment. You might do better to get a second truck, to follow with the trailer.....maybe even put a TC on it, for 2-3 of the guys.