Corner trim & leaks

[dnaraG_1M]

As I am finishing up one part of a restoration, I'm at the point of
needing a "sanity check" about putting the corner trim back on.

Background:
The former owner(s) allowed water intrusion at the
corners where the metal skins meet. Rot was extensive and required
me to rebuild the front wall, part of the rear wall and sides. That's
done and I'm putting it back together now. But - at all costs - I want
to make sure there are no future leaks. To that end, I have done
several things.
First, I covered the corner wood with rubber membrane material that
is supposedly self-healing. Two inches on each side of the corner are
covered.
Second, when I put on the skins, I ran a bead of Dicor down the corner
to prevent any sneaky water from reaching the unprotected wood.
Third, I ran EternaTape down the corner, overlapping the skins by
two inches.

Now:
I was ready to put on the corner trim, but am wondering if that
is really a good idea. The EternaTape has *NO* breaks or gaps in it.
Putting on the trim would require penetration with many screws.
Even if it is self-healing, would that not be an added risk???
On the other hand, maybe the trim is needed for some structural
reason - stiffening the skins at the corner??? Preventing wind from
ripping off the side skins??? Something else???

I am now up against my lack of knowledge of the whys and wherefors
of TT construction. Something that will ride down the highway
at <n> miles/hour and vibrate itself all to h-ll is a whole new
ball game for me. Very different from the simple flatbed trailers
in my past.......

Any suggestions and/or insights would be helpful......

cheers,
johnd