Dave - I have spent the last couple of weeks fooling around with my seats and mounting them. I am very motivated to use sliders but that has introduced a myriad of issues. To stay within the confines of the floor pan they need to be mounted as far aft as possible to catch the floor pan steel. One of the bolts ends up in a frame member but I'm OK with that. I welded nuts to the inside of the tracks to be able to bolt from the exterior upwards. Needless to say, this is pretty fiddly.

Just today I was contemplating welding a 3/16" steel strap "box" with countersunk bolts tacked in place to mount the sliders to. That way I can drill through that bracket anywhere I want. Lots of ways to do it but some are definitely easier than others.