Pronghorn are not big animals. If you know how to process a deer, you can process the pronghorn yourself. You could process it on site, out there. If you are hunting on a ranch, the rancher might give you some place you could do this (like a clean board on top of a couple of saw horses). I processed and wrapped 2 whole pronghorns in a hotel room in Gillette one evening in October 2004. There are advantages to that. You have finished meat and you can pack dry ice below and above the meat (separated by 1/4" of newspaper or other non-heat conducting stuff) and really freeze it and know it will stay good.

I have heard that the hair on pronghorn slips very easily. By this is meant that the hair strips off VERY easy. You might end up stripping off lots of pronghorn hair from your cape if you aren't careful. Have you thought about having the head done there and shipped back to you? I did this. The shipping is somewhat expensive, granted. Something else to worry about, in case you didn't have enough already.