Nash..... you didn't say how old the rig is or how long that the caulking has been in place.
The 'corner' seams always seem to flex more than others and are always a concern for leaks.
Good thing you are on top of it !
It is always best to remove the old caulking on most seams (with exception to the roof) to assure you are getting good adhesion.
Preparation is the key.
After removal of the old stuff give a good wipe down with a rag dampened with white gas, Naphtha, ...and of course as with any flammable fluid...Use
Caution. This will remove any residue and leave no oily film...dries quickly.
For a 'neat' job I always mask both sides of the lines to be caulked leaving margins for the caulk to lap the seam. Run the caulking along the seam then with a finger dipped in soapy water shape the bead of caulking between the masking tape. After a section....remove the tape and again run a soapy finger over the edges of the caulking sealing it where the tape was removed.
This is a little labor intensive way of doing it ,But the clean and tidy results are worth it....better than 'free-hand-caulking'.
'07 WildCat 30 RLBS ~ West Coast Edition ~
Trail Air - Tri Glide Pin Box
2000 F350 DRW 7.3 Diesel Lariat 89k miles
Edge programmer, 4" SS exhaust turbo/back
Vancouver Island, B.C., Canada