I'm thinking about getting the T13... it is on sale right now. My only issue is that the larger footprint (4'x30" x 18") is different than the T10 I already have on order. Do you think the T10 would stack on top of the T13 (it is 2' wide).

I'll have to think about the RHP... I may go with heat tape for now and then upgrade to an RHP if the heat tape isn't working for me.