I've not done a quarter, though I did some white-tail deer from Idaho for my neighbor a few years ago in my GOSM. The cuts were hard to identify as they are so small, but looked to be loin cutlets (backstrap), and some other assorted small steaks. I did 3 batches for him in one smoke, all smoked with hickory, and seasoned differently/packaged seperately, so he could tell me which he liked best.
The dry rubs consisted of pretty simple blends. CBP, white pepper, some cayenne/chili powder, kosher salt, and paprika. I don't have the recipes anymore as it was a one-time deal. Main thing in my mind is KISS method here.
The meat was a big hit...all of it...when asked which was his favorite, he said everyone (guys at work included) liked every bit of it, so I guess it was all good.
Upon reading through Dutch's post on smoke woods, it looks like oak or maple would be good choices for smoke, with ash being another good possibility for a nice flavor.
As far as internal temps are concerned, will it be sliced or pulled? I would treat it according to that, 165* being the minimum as game meats shouldn't be eaten without fully cooking.
The hind quarter will have some tougher areas and some really tender meat, so consider that as well with finish temps...maybe treat it like a pork picnic and go for fall off the bone? You may want to ask you friend how he might like it done before you get too far into it. Make sure he understands what the two finish styles will do for the texture/tenderness. I do think you could still slice it at 190 and get fairly tender throughout.
If you go for the pulled, have a large roaster pan ready and foil for a tent...just foil won't hold up very well, even with multiple layers with bones and pieces of meat that large.
Run chamber/grate temps like you would for a large butt or picnic (240-250*).
Don't sweat the particulars on smoke wood and seasonings, do what you can with what you have, & KISS it...it'll be fine.
Just some thoughts there for you to consider. Sounds like a great smokin' project...good luck & please do post q-view!