Splint, I’m still confused. My original plan doesn’t call for the removal of any wood from the doors. The T-track would be surface mounted with closely-spaced screws (maybe up to 5/8” long). Then a cosmetic cover would hide the track. (My rendering, which uses SU’s X-ray display mode, makes that hard to see.) But I take your point that a solid steel bar will be stronger than the track. I was just thinking that the squarish structure of the track would stiffen it sufficiently.
Oldtool, thanks for your feedback too. I didn’t realize that such small (3/4” cross section) battens would work. That’s good to know. I’m pretty certain that the T-track remnants I have are stiffer than a 3/4” square cutoff (from a rip) of the maple I’m using. Lowe’s and Home Depot in my area sell pine, poplar, and red oak (or did the last time I looked). I guess the oak would work.