Not clear what you mean by 'civilian jobs.' Most people on this board are emergency docs - working in either academic medicine or the private sector. There are a small number of military jobs, not a lot in EM. Most grads of wilderness med fellowship will either work in academic medicine and have wilderness med as their academic niche, work in private EM and do wilderness activities on the side, and a small number will be able to carve out a career that is entirely wilderness med - (ex. event consulting, expedition med, doc for the national parks, etc.) The best reason to do a wilderness med fellowship would probably be the connections you might make. A motivated person might be able to do most of the same things without a fellowship.