Your the man!!!  Great pics.  I am sure the undercoating will be fine.  Do you think it would be a good ideas to spray some type of sound deadening while you have the room.  Not sure about the clearance??? Still curious if they sent a template or if they just give ruff measurements for your cuts and fabrication.   
Thanks for taking the time to share your journey with us. I cant wait to see this sleeper rip out of the driveway for the first time.