1968 Williamscraft - honeycomb corrugate in flooring???

I would frame the floor the same height as the cardboard and insulate with rigid foam. That cardboard stuff is a failed experiment that they tried and gave up on. Yuk.

The water inlet is connected to a water line inside. You'll have to look at the other side and see how to cut or disconnect so that it will come loose.

Cut the bolts with bolt cutters or a sawzall and buy new. Not worth messing with the old ones...

Does anyone have pictures of how they repaired their sandwich floor? The order they did it in? I took out the skirt and sill on the one side and the floor was nestled between it (bottom and top part of the sandwich. Not sure how to proceed as the other side is good. Might have to take out the whole floor from the back to the wheel well where there is a joist. Not sure how to join the new and old sections.

At long last, a kindred spirit. When I first brought my cardboard floor here I got a combination of head shaking and disbelief, but not much advice from experience because much of the expert knowledge here is in 50s campers that were built better for repairability.

One member, RinTin offered some wisdom from his woodworking experience. From that, I decided to start over with the floor using a pseudo joist method, but with much thinner boards as spacers to keep the original floor thickness of only 1.25".

Once I was done I was worried a lot about the integrity of walls attached to the sides of such a thin floor because most campers here have floors+joists twice as thick. To ease my mind, I added some cleats inside the cabinets to further attach the walls to the floor.

To this day, I can't think how I would have repaired the original floor. The factory gluing of the honeycomb was integral to the structure and much of my rear was broken and rotten. You can browse through this blog and see all the times I nearly hauled it to the dump. It's a lot of work to re engineer a failed 60s experiment but I'm glad I tried.

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My original plan was to lift the body off the floor but my walls ended up so far gone, it was easier to remove them. There are examples here and elsewhere of jacking the body up to remove the frame and floor so you might start there. How thick is your floor? Mine was so thin at 1.25", I didn't trust anything but thick plywood to replace it, but if yours is 2" or so, you could consider a more modern sandwich of 1/4 ply-1" foam-5/8"ply floor with a joist structure that matches your frame and cabinets.

One note about the frame extension. I would recommend using all angle iron and not heavy C channel. I think the added weight in the back has unbalanced the trailer and made it more prone to "porpoising" if I don't heavily load the front.

If it's built like mine and 75% of the campers on here, the walls are built first and then attached to the floor which sandwiches the wall plywood between the floor and the framing.  The ceiling is similar, applied from the outside and attached to the wall tops.  This gives a rolling pile of sticks some unibody structural strength and why VTT advocates only repairing campers from the outside with the skin off.