This is what I had to do to my car when I got it (wow guess 4 years now) of course I had to pull motor out, and ended up taking rest of car apart, since I'm in the, might as well replace everything mode, got motor rebuilt, rear, ect... so anyway, what I did is, on LMR they sell the frame rail kits, well mine was only bad in that spot where the k-member bolts go like yours, the drivers side was the worst, pass side wasn't bad at all, but I did the same repair to it anyway... so I removed everything, including the k-member... I found on another form thread, the guy who makes the frame rail kits that LMR sells (I forget now who) so I hit him up, to see if I could buy just that outer covering part (the one that the top k-member nuts sits on in the strut tower in the wheel well, and if he had any extra rail sections, so I would have the same metal thickness...ect,,, so I bought the stuff from him... those stock crush tubes are just bent sheet metal, and are not even fully connected as a cylinder... so what I got from him, was a bottom plate that fits in the frame rail, that the crush tubes sit on, the crush tubes (which were real tubes, and the out part in the wheel well that the k-member nuts sit on top of, and a couple small sections of scrape frame rail they had they was left over... I didn't end up using the crush tubes he sent, I had some pipe that was a little thicker 1/4 I think, so I cut 6 of those (3 for each side) welded them to the bottom plate. I cut open the section, and sandblasted and panted everything, then tacked that bottom plate into the bottom of the frame rail with the 3 crush tubes on it... then I painted it again... then I welded new metal to close it up, and also the new out side top cover in the wheel well... I also had to buy new k-member bolts... I found a set of stock ones on e-bay, they looked almost new... (I think the bolts from ford are over 22.00 each if you can even get them). got the k-member bolted back up. Then I got the Eastwood internal frame coating stuff. and sprayed that into the rails once i had it all button back up. I used a lot I really wanted to make sure it never rust in there again... lol.... I'll look for the pictures when I get home and post them up...
I feel this should be stronger then it was new... since all they did is spot weld everything, and those tubes were just thin sheet metal and not even a fully formed tubes...
will be putting the motor and everything else back together finally this spring, hopefully next month when the weather finally warms up...