Les & Carole-
1) Welcome to iRV2 and the Alpine Forum!! Hope to see you around here and at some ACA & local area Alpine club rallies in near future.
2) to my knowledge we don't have an accumulator on the brake system. The "power" for the power brakes is the radiator fan motor & power steering hydraulic fluid system which on your coach is probably off a red trans PTO (mfgr = Chelsea) located on the PS just behind the battery box on the transmission (the crude device just forward of the red Chelsea PTO is the hydraulic pump). This has power when the engine is running and none when it isn't. There is an auxiliary 12V pump on the master cylinder that provides boost when the key is off; you hear the growl of that motor when you step on the brakes w/key off. Some rigs have an accumulator instead of the aux pump to meet DOT req'mts for a secondary boost source in case brakes need to be applied when engine isn't running. That may be what "BrakeMaster" is referencing. How htis affects your installation I couldn't say; I'm not familiar w/BrakeMaster.
3) since you have a late model Alpine and are messing w/the brakes, check this thread
on rear brake line across the axle. Now might be a good time to deal w/that if you find you have an issue. IMO if you have no kinks, the only issue is whether you need additional support for a cantilevered end of the cunifer line; the issue is fairly well discussed in that thread (don't let the early part of the thread scare you, the problem & solutions are identified after several posts, but the original post lays out the possible down side if unattended and you have a weak cantilevered tube end).