I dont think I would worry about water soaking the foam insulation at the dog house area (unless you plan on crossing a 4 foot deep river
The dog house is in middle of the coach and the engine/tranny would block most of the splashing water from nomal puddles.
I ever had any problem with my Axis and it was installed two years ago. I also did my entire fire wall and under the dash (from both installed from the engine bay). This cut out ALL of the heat and a ton of noise. Much better than stock.
Plus the engine heat should dry out any wet spots quickly.
For the most part went with the name brands (Dynomat and Fat Mat) and they held up great. Very sticky so they should last for years.
I also tired some cheaper brands but they were not as sticky and not as thick. So you might want to stick with the name brands (IMO).
I didnt save much buying the cheap stuff to justify it.
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, TPMS, Surge tank, Tornado flush, Viair Compressor