If you are handy it may not be that bad of a fix. My wheel well was never sealed correctly from the factory. Water collected between the osb floor board and the metal wheel well casing rotting the floor. I thought my trailer was done and had estimates around $5,000 to repair. I did it myself in a week at around $150 in material. The biggest labor was trying to remove the kitchen cabinets. But with some strategic cuts to the carpet and flooring I was able to roll back the vinyl flooring, removed the rotted floor, fortify with gitrot along the edges to prevent any possible spread of the rot, replace the flooring joists and insulation, roll the flooring back into place and replace all the cabinets, plumbing etc.. You cannot tell it was ever done. And yes my trailer has aluminum studs in the wall that are directly attached to the framing so no rot and the walls were not built onto the floor.