It's not RAM, just the dealer. Often the conversion is 'in the way' and greatly complicates things, especially any kind of electrical problem. I'm surprised at the refusal to work on brakes but who knows what some RV builders mess with and tap into. The dealer has likely had a number of instances where a conversion tied up a mechanic waaaay too long (causing service delays for regular customers, etc) so just made a blanket policy of banning all campers to avoid the frustration.
Also, but maybe not the case there, not all RAM dealers can service Promasters due to size restrictions.
Also, but maybe not the case there, not all RAM dealers can service Promasters due to size restrictions.