Hi Denny,
I have really enjoyed reading the metalmeet forum.
http://www.metalmeet.com/forum/index.php These folks are metal workers with very high standards. Also there is an International Metal Meet in Oblong, IL coming up Oct. 12-19th, 2010.
So not being a professional body man I am a bit reluctant to make any suggestions but since it's only a bit reluctant I will anyway.
On some of the inaccessible panels on my truck I have drilled large 3 or 4 inch holes with a hole saw in the interior panels. That allows me to clean things out and get a good coat of rust protection sprayed on. Also allows access for a curved dollie. The holes can easily be welded back up or left as permanent access panels. Since I'm hoping my trucks will last another 100 years or so I have just installed covers with screws so I can be sure thing stay nice and rust free.
