You are out of your depth. Winnebago motorhomes since late 60s have been laminated wall construction, and if thoroughly delaminated, laminated wall are not structurally sound. Structural strength comes fromthe bond of skin, inside and out, to the core. Early Winnebago models with steel framing and metal skins had more framing inside the wall, but for your vintage the laminated wall is it.
Some consolation, a delaminated panel wall is probably still stronger than a built up framed wall, a technology that stay with some mass market manufacturers well into the 90s and is still used by premium RV builders. But then, strength, or torsional rigidity, of a single wall panel tells you little about the strength of the box as a whole.
What yiu have is likely usable, but you are not going restore it to original condition without spending as much as it takes to buy a new one.