Hi: Mary Ann in MN... I have a similar repair to do on my ''project'' Boler
. I plan on making a cut out in the bottom inside panel of the door then cover it with a vent plate. Then I'll scoup out the wet swolen fiber board filling and install some bent 1'' square aluminum tubes in the bottom of the door liner and screw thru the inner door liner into the tubing. I'll use speed clips to screw the vent cover in place. I'll try to keep my digi cam. handy to record either my success or...whatever!!! Lastly I'll re seal the window with new rubber back seal and vinyl glass seal from Vintage Trailer Supply for the Hehr door window, which caused all the problems to start with!!!
Alf S. North shore of Lake Erie