If the roof material is sound for the majority sake, I would pursue a repair of the bubbled areas. There are many products out there that will accommodate repairs. Establish repair boundaries using some form of masking to get better finished results, whether brushing or spraying.
My last repair of roofing included a large gap (1/2") at the leading edge of the RV where the front cap joins the roof. I used mess screen imbedding in the sealant with a second coat the following day. I used a product named "Ultra Roof 1000". It is a white polymer elastic coating. Third year after repair yields no degradation.
Be sure to replace any rusted fasteners with stainless steel equivalents. Cost a little more, but your time is worth a lot.
BTW: If storing where it potentially freezes, be sure to drain all water lines, remove charcoal filters under sinks as applicable, drain the water tank and leave the faucets open to facilitate drainage. Best of luck with your rig.