While the Tamiya track sounds good, there are a couple of issues that I see. I don't have a Tamiya car that I can turn into a rally racer (unless we want to let me run my Clodbuster, heh), and that is definitely a haul for me. I also think that limiting it to a single make would not be the best plan.
Let me work on a rules package this week and I will post it up. I am definitely thinking that we go along the lines of USVTA so that folks can use old TCs that are sitting around.