Not sure about Montana but I know in Idaho you can hunt with a crossbow if you get a doctors note saying you can't draw a bow. My pops used that loophole for a while while I lugged around the real deal. Hunting elk with a bow takes balls....gotta get real close. I have been up to within 6 feet of one....you get a real close up look in their eyes at that distance!
Last I heard was they were trying to change the crossbow law here so anyone can use crossbow during archery. I dont think it's been voted on yet. I know people with disability can use assisted shooting bows. Pretty much a crossbow but held vertically. Not sure with an actual crossbow though.
Close elk encounters are crazy! First bull I ever encountered came in under 20 yards screaming his head off. Dont realize how loud they are til one about blows your eardrums. Last week had a sow griz with 2 cubs at 15 yards, luckily she spooked as soon as she saw us. Bull moose in rut has been scariest situation for me. Ain't no joke in the woods!