I was just looking back at your build, and one thing caught my eye:
Your Webasto exhaust pipe is a pretty long horizontal run. I am a bit worried that you are going to have an accumulation of condensate water in that pipe that over time will lead to corrosion. You might consider creating a low spot upstream of the muffler and drilling a little weep hole at the bottom of the pipe.
You can buy a commercial drain like this:
but a tiny hole does the job without creating noticeable extra noise.