I put the regulator upstream of the filter to protect both the filter and the trailer plumbing. Forgot to do this once with a cheap inline filter and pressure blew the casing apart - lesson learned!
80 psig is way too high for the Airstream but both regulators should prevent that. No answer on the other question because I am not sure of your piping layout.
Good Luck.
__________________
Todd Mizer
2021 25' FBT Flying Cloud
Ford F-250 6.7L
WBCCI #6826
We have Year-Round Courtesy Parking.
This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.