If it has a steel frame and aluminium cladding and they have neglected to follow basic isolation procedures, you may end up with corrosion and blistering of the paint for several inches around each fastener. As far as I know, there is no way to stop it short of removing the cladding and doing the job properly.
I have an MC8 and the previous owner - supposedly a coach builder - reclad it with aluminium instead of the original SS. He skimped on the installation in places - especially the door - and there is blistering under the paintwork in many places.
BTW contrary to popular belief, stainless steel is not immune to electrolysis problems and some grades are worse than others.
Tony Lee - International Grey Nomad. Picasa Album
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RVs. USA - Airstream Cutter; in Australia - MC8 40' DIY Coach conversion & OKA 4x4 MH; in Germany - Hobby Class C; in S America - F350 with 2500 10.6 Bigfoot camper