[Yosemitest]

But wouldn’t a crossbow take up too much room in his pack over a one week hiking or camping excursion?

[moose07]

Not if wrapped up and mounted on the outside of the pack.
It is something to discuss with your friend.
I've always found them must easier to use when 'things' are hurting.

[Charles Martel]

But wouldn’t a crossbow take up too much room in his pack over a one week hiking or camping excursion?

Not really. There are packs made specifically to accommodate crossbows (basically, they split the outer compartments into two, offset to either side of a vertical channel where the crossbow stock sits, pointing upward - tips of the bow right behind each shoulder).

You stuff the pack first, then strap the crossbow in place. I think some of them are arranged so the crossbow can be "drawn" up and over the shoulder for quick use.