Can't help you on the brake line, other than suggesting that the shop drop the tank.
I have done a DIY replacment of the rear shocks on a '99/'00 Dodge Roadtrek. I've been an amateur wrench-twister for the past 50 years. It was not an easy job because of the the chassis modifications by RT, but was do-able. But that model year is somewhat different from yours, since Dodge did a redesign in '98. I'm not sure what changed underneath.
I suspect that you may find it easier to get both jobs done at a small RV repair shop if there's one in your area, but it'll likely be a lot of labor over and beyond doing the same job on a plain van. I'd try to stay away from big RV dealers' service departments if you can.
Jim, "Laughing stock: Cattle with a sense of humor."