Im not a moderator and don’t know the backend of managing this site or any other forum, so take my opinion with a grain of salt.
I don’t see the concern with having another sub-forum, particularly about vehicles, something that 99% of us have. Some people are more into vehicles than others just like some are more into traditional archery or reloading. If a member is looking for info about hunting vehicles, vehicle recovery etc., why send a them to a different site/forum to get them the info they are seeking? Why not keep them engaged here? It is very difficult to get people’s attention and follow sites, forums, blogs, etc. but Rokslide has done well building a loyal following. I think a vehicle section is a natural extension for the forum to continue building traffic, engagement and getting members to the site.
Additionally, I see it as an opportunity to potentially generate more advertising dollars for the site. If a sub-forum is robust enough perhaps there are companies that have vehicle products that would like to specifically target hunters.