Insulating the Belly of my TT

Yes, I have the coroplast now - and you are right, there are several large gaps in the fit and finish. And it is just inserted above the flange of the I beam frame... lots of air leakage. I could just run a small bead of foam insulation around the edge! And yes, my black tank, fresh water tank, and one grey tank and valves are all enclosed - I have the rear kitchen and a galley tank located at the rear of the trailer has the drain line exposed for 2/3rd's of the length of the trailer. Maybe I should place a valve at the tank before it exits the heated space...

Thanks for the ideas.