The sidewalls aren’t attached to the frame, the floor joists are and the sidewalls sit on the floor joists. Ordinarily the sidewalls are supported by outriggers spaced at regular intervals and the lags hold the bottom plate to the outrigger. If the lag bolts have torn out you’d just have to make sure the fastener has a large fender washer on top of the bottom plate to pull it back down onto the outrigger. A photo would tell us a lot more.
That's not what I was referring to. The lag bolts hold the sidewall to the upper frame where the 5th wheels have the bedroom (upper deck) and where the pin box is, they are screwed though the inside of the frame into the sidewall .The holes in the frame are fine its the wood in the wall that the lag bolts have pulled out of.
Regardless, you'll either have to lag the bottom plate from a different location or gain access to the inside of the wall and insert a bolt with washer from the bottom up through the original hole and secure it with another washer and nut to the bottom plate. A carriage bolt would work.
