On ours after taking delivery I used black silicone caulking to seal the under penning 8 tubes of it, and 2 can squirt foam, just to seal up the under pinning. There was a gap down each side of the slides that I also used black silicone it looked like FR forgot to seal those gaps. I took off the divider panel in the storage compartment and used spray foam to seal all the plumbing penetrations also under the sink were plumbing penetrations. In each corner of my slides I can see day light coming thru but I haven't decided what to do about that yet. Good luck with sealing the air out.
2014 Palomino Columbus 3650TH
435AH 12V VMax Charge Tanks, 520 watt Monocrystilline Solar Array, Morningstar MPPT TS-60 CC,Morningstar Remote,Cotek True Sine Wave Inverter,Cotek Remote Controller,50amp Progressive Hardwire Surge Protector
2015 Dodge 3500 6.7L 4X4
2011 CanAm Commander XT 1000