Kozzy; the reason most of us due the eternabond tape on the roof is as a preventative measure. Taping the length of the trl at the roof edge helps preclude any chance of a leak in the gutter area, and a tear in the rubber if you accidently rub a tree branch. Doing the seams at the junction of the front and rear roof/metal seam is because this area is prone to leak due to flexing of dissimilar materials. Also the caulking around the sky lights, etc is prone to crack and leak, and if it does while you're trl's in winter storage you could end up with a soggy roof. It's just a case of "An ounce of prevention is worth a ton of cure" in this case. It'ss headoff any possible issues down the road.
2012 Winnebago "Journey To Insanity" 40U
2008 Dakota Sport 4x4
2004 Subaru Baja - DW's
2006 Honda Shadow Aero - TOAD for now.