Yes, it is a weak spot, one that is not unique to UNIMOGS. As you no doubt know, the rubber gasket is basically an I-beam shape, with the inside
Of the channel in the gasket holding the glass, and the outside channel latching onto the weld / pinch seam which defines the opening.
Water then, actually has two places to collect - the inside and outside channels. The inside one is not much of a threat, since it is pooling where
It Is just glass and rubber - nothing to rust. It can lead to issues with the Glass, especially if laminated, and bubbling and fogging can happen.
The rain hits the glass, runs to the edge of the gasket, weeps In and tends to follow gravity , pooling at the bottom.
The other channel, the outside, does the same thing, and it is worse because it is trapped next to a painted surface, and worse yet, one that has an exposed, essentially unfinished edge. The paint bubbles, the raw steel is exposed, and the rust demons get to work. The 4 corners can be the worst hit, but really, the rot can happen all along the opening.
What to do ? Well, 'dents' at the lower corners could work, but they don't do a thing anywhere else. I have photos that show severe rust rot Along the the top and into the top corners, so gravity does not come close to getting all of the water to the bottom corners.
I think the number one thing to do is to invest in a new gasket. Before you even take your windshield out, you can check for problems with a Plastic putty knife or trim tool, opening up the lip of the gasket and looking underneath. If you have rust, you'll see something, and then you'll See more when the glass is removed.
Next, even with a new gasket, your local Auto Glass Pro (or pros) should be be consulted. The guys I know are of two schools : Goop, or no Goop.
Some will run a bead of glass sealer/caulk all the way Around after The installation, some think a 'Dry' installation is best.
Of course, salted winter roads make it all that much worse.
Instead of dents, I'd suggest thin nylon washers or shims that will create a drain or air gap, without dinging your paint. The gasket will hold them in place. Like a dent, they will actually open up a channel for more water to get between the gasket and the paint......but then they also open up a drain and some air flow to dry stuff out. With a dent, you are committed, but with shims, you can move them around or take them out if you want.
Honestly, I think a new gasket and a smooth mating surface ( good paint, not rust ridges) is the best, and then just
Monitor it.
More later, but I have some work to do..