Hi Josh,
I just found your post. I have been into the Lippert rack and pinion slides, the Barker rack and pinion, the DeWald (Power Gear) rack and pinion before, and while my camper has the Lippert rack and pinion setup, the trough in the floor was made by my camper manufacture.
I can state this though, the two end walls of the slide is where the big support of the slide is going in and out. The walls are rigid, including the long outside wall and they are structural. But the long slide floor itself (the part that is open to the main camper) normally does not have a vertical support to the ceiling in the middle area of the long open section. That center floor area is weak unless the slide is full out being supported by the camper main floor.
To help better, what type of slide drive drive system does your camper have? By your description it sounds like a rack and pinion system, but there are several brands on the older campers. Lippert, Dewald, Power Gear, Barker etc.
Is your slide setup a "flush floor" system or an "above floor" system?
The flush floor setup is more flush between the main camper floor and the slide floor when the slide is full out. There is a rug flap that covers the gap between the two floors. This flush floor system has a cam type of plow so to speak to lift up the entire slide off the main camper floor as the slide comes in and goes out. This type of slide setup most often comes in going up hill on an angle to get the slide floor up off the carpet or floor vinyl in the camper. When the slide is in, the long tongue of the slide is several inches up off the floor.
The above floor is at the name states. The slide floor is on top of the main camper floor, there can be a 1" or so bump (the actual slide floor) to walk from the main camper floor up into the slide when the slide is out. This slide moves more straight in and out. There is no cam action lifting the slide up off the floor.
The plastic floor slides, LCI calls them slide slickers, helps the above floor system not drag the floor as much. On the flush floor system, often you can adjust the system to lift up off the carpet/floor and the slide slicker is not needed as much, but sometimes added as the system gets a lot older.
Where I'm going with this, I do not have you exact camper, but I have worked on some of the older Keystones and other brands to repair older slide setups that have deteriorated over the year with sagging slide floors, sagging main frames, leaking slides, and just plain high drag in the system, but it helps to know what you have on how to help better. Do you have any pics of the slide drive system under the camper and area the slide floor to the main slide floor area where you added the rollers? And some inside the camper too.
Hope this helps
John
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.
