Hi polobeer
I have the same problem! Many years ago I built Alfred from the PBM kit. I had lent my original plan to a friend, who then went and died! It took over a year for his widow to sort through all his stuff, and send it back to me. I had already started the same tug, but from Tyne Models 1/32, much bigger than PBM's. Unfortunately neither plan showed wheelhouse interior. I did get a CD with photos of Crosby from Brian Close, with a couple of pictures taken from the wheelhouse doors, so was able to work out roughly what went inside, not perfect but a reasonable interpretation. If you want to contact Brian, there is a link from Tyne Models website to Brian's and he is very helpful I have found, and a super modeller, way above my standard!
Best of luck with your build, mine is now operational, but has a fair bit of detailing to go to complete.(sails well though!)
Danny