Paul,
My new head stays are made from some 3/16" 6061 plate I had. The sides of my Flatlands (approx 1/8") are overlaid with an additional 1/8"+ 6061 plate with a bend around the front edge for strength. This is screwed to the sides of the Flatlands, and the ends of the GP braces. The original Flatland mount was cut off and relocated back and up to match the new head stay mount. So now you have at least 1/4" total tied to the frame through the GP braces, with at least a 1/4" clearance to the side of the rad. I also drill and mount my shrouds at the top to the top brace with a rubber isolator (same as front pipe mount), so the shroud can flex a bit in a hit and not rip out or bend the rad tab. Its quite strong. One rad took a baseball size rock kicked up by the bike in front, dinged the Flatland grill in some but NO bending rearward. You can get more radical and make head stays with the mounts farther back, but then plug access and flex become issues. All you can expect to do is eliminate/minimize low speed tipover damage, there is nothing of practical weight/size that will keep the rad from getting wrecked in a warp speed encounter with a tree. I got one of the first '07s, and had limited rad guard options at the time, so I did what I had to do. IMO the '07+ rads are cheesy and weak compared to the older rads, and I would not even ride the bike without protection as I have no nice place to fall here. Frontal protection is also a must as I have proven several times.
As far as tying the rear mounts together with no support, thats how the Flatlands were mounted on my nephews 125 GG by the previous owner, as there is no head stay like the bigger bikes. Not the best solution, I just have no time to fix it.
Now, to figure out how to build a clavicle/shoulder cage.
