rear corner exterior trim screw replacement

I have a 2004 wildcat 29BHBP on the last camping trip I noticed the trim was seperating from the fiberglass siding of the camper at rear exterior corners on both sides at the very top. I did not have any caulk with me at the time so I used duct tape to seal the opening. As usual while camping rain was headed our way and I was making a quick effort to keep water out of the opening. The guy at the camper store sold me some new trim strips and told me to take the old inset strip off this would expose the screws that join the corner trims to the camper. Then to use larger wood screws to pull the trim back tight and caulk.
Just wondeing if anyone out there has experienced this before and what size screws you used.
Also, the duct tape though it worked left a gummy mess on siding any suggestion for cleaning would he helpful.

WD-40 works well for removing gummy sticky tape residue. Also works on sticky price tags.

Thanks I will try and see what happens

I had the same problem. They used to short of screws according to my repair facility. I had them repair it while they were fixing some other items.