I'd split the cost amongst those that go. I'd split the meat amongst everyone, rookie and no-go included.
You're starting from scratch here. You wanna build a group that supports and values each other for years to come. Sacrificing a few roasts is an inexpensive way to do that.
That's the right attitude to have.
Being from Newfoundland we don't have deer camps, but we do have a long tradition of group moose and caribou hunts where just one or two of the group is the actual license holder. You can't buy big game tags over the counter, but instead have a progressive lottery where your chances of being drawn go up the longer you've gone without a license via a "Pool" system. Preference is given to partner/"party" applications. The more desirable MMAs have many more applicants and are thus much harder to get. A lot of guys will buddy up with another 2-4 hunting buddies and have their pools staggered so that their group is virtually guaranteed at least one moose license per year.
If travel is involved the party members split expenses and meat equally. If someone can't make it due to unforseen circumstances they'll still get their quarter of moose. Kicking in to help with gas is welcomed but not mandatory. We basically view such situations from the perspective of "...There but for the grace of God go I." Someone who makes it a habit of ducking out on the work and doesn’t contribute to expenses is shown the door.
To the OP, have a chat with the two young guys and your other buddy who can't make it. If it were me, I'd be willing to split everything equally, expenses and meat, but with a clear expectation of reciprocity next fall. The guy who didn't finish his hunter safety course and couldn't obtain tags should pull camp cook and roustabout duties to make sure he pulls his weight, but don't be a #### about it. Having pulled such duty myself, I'm thankful that I still had the opportunity to go scouting, do some stalking and pitch in once the real work began after we had a moose down.
On the flip side, we did have one guy worm his way into our group at the last minute one time. A friend of my brother, the guy showed up an hour before we left with nothing more than his tags and sleeping bag. No gun, no grub and claimed he had no money but would kick in his next payday. Against our better judgment we took him. It was the one and only moose hunting trip that I regret ever going on. The leech ate our food, drank our beer around the evening campfire, barely turned his hand around camp, never shut up and was constantly running his mouth and stirring up $hit. To make matters worse, hunting conditions were horrible that year with heavy rains preventing us from getting across the river to our MMA more often than not. Our two caribou licenses went unfilled and just one of two moose licenses were filled, by, you guessed it, the leech using a borrowed rifle and ammunition. We did the bulk of the dirty work field dressing the small bull and skinning the quarters. Not a lot to show for two weeks in the bush.
We dropped off the quarters to the local butcher to age upon our return home after a five hour drive. We didn't hear a peep from the leech for a month when he showed up with 30lbs of moose sausage. No gas or grocery money, no 24 of beer or even a bottle or two of good scotch or Irish whiskey. The sausage was inedible and I later learned by chance that the Leech had only dropped off the sausage because he hadn't liked it either. Class act!
Our group moved on and tried to forget the entire sorry experience, looking forward to better times next year. Believe it or not, but the leech had the balls to wonder when we'd be leaving for "our" annual hunting trip the very next September! Best laugh I'd had in ages!