Antelope - you better get something flat and fast. Elk - you better find someone who has an elk mount. Go look at how big those things are. It's. . . . staggering. I was all gung-ho on elk hunting about 10 years ago. Then I saw a mount. "Oh NFW. That's actually TOO much meat! Plus the mount. And where the F am I gonna put that mount???? It's HUGE!"
On Bladeforums, there was a guy that would go antelope shooting annually with his custom Cooper. Damn. That guy could shoot. It was a 20-something caliber (204??) in something crazy fast. But antelope see you from a LONG way off. Driving around Montana BLM land, I was shocked at how fast they took off if they even sensed you.
I'd nix the idea. As others have said, it's going to cost at least double. Elk hunts alone (per person) are going to run $5-6K. Add in the extras and you're up over 8 easy. Per person. That's triple what you planned.
Hate to be that guy. But it might be better in the end. Find a different trip or a different idea.
It's a great idea. Sometimes, it's better to kill a "cool" idea early and just move on instead of trying make it work and come up with 42 different compromises that leave a bad taste in everyone's mouth.