You don't need to worry about needing a slider rail to install the trifold cover. The cover connects to the foward end of the bed by the rear window with plastic clamps that grip the underside of the rail. The aft clamps also grip the bed the same way, but are spring loaded for quick access to uncover the bed, and fold up. Not sure if you can install it with a drop in liner.
I installed the TipTop cover from Amazon last Friday morning. It was a 10 minute install, despite temps being in the low 20s. Then I went on a 900 mile round trip to Canada, had zero issues, just checked on all connections during one stop. I don't drive all that fast, but occasionally hit 80 wihle passing.
Most installations are similar to the way @Suzukiridr14 described it. In my case, the cover was clamped to the bed on the sides, not right under the window, using 4 T-screws and short metal plates. The clamps near the tailgate use the same type T-screws, but clamp down the bed with quite some force.
I didn't mean it clamped to the rail behind the window, (thank you for correcting me) I was referring to the foward section of the cover. it clamps to the side rails like you said.
Man, I read your description and was thinking that I would've preferred to have a way to secure my cover that way. Or at least have one or two extra clamps right against the wall under the rear window.
I have the Ford tri-fold, I installed in about 20 min on my XLT LUX FX4.
just put some weather stripping along that edge (close to the bed as possible). No need/reason for clamps below the window. The side rail clamps are more than enough to hold it down.
Probably something I will look into next spring. We got 6" of snow Friday night, I'm not going to attempt anything that requires an adhesive to stick to something else.
