Replacing Coroplast Screw Attachments & Adding Support

[goodellj]

I have been wanting to replace the OEM self-tapping bolt/screws that hold the coroplast to the frame of my 2012 3150RL. They are very corroded and some appear to have worn through the coroplast and are not providing much support. I would replace the OEM self-tappers with stainless and also add stainless steel fender washers. I'd also like to maybe add some 1 1/2” x 1 1/2” angle iron to support the coroplast,, although I'd like to find something stainless or non-corroding. I have found that the screws are so corroded that the heads will break off when I try to remove them.

Can anyone offer suggestions on how to remove the old bolt/screws? How hard would it be to simply add new screws and leave the old ones? Do these self-tapping stainless bolts need a pilot hole to get through the I-beam of the frame? Do I need a special high powered drill? Is there enough clearance between the frame and the holding tanks inside the frame to avoid damaging the tanks? I don't think I have ever tried to drill though something as heavy as the I-beam of my trailer frame. Do I need a special drill bit for a pilot hole?