Haven't looked that closely at the '88 Winnie we recently bought - but seems to me there is a brake fluid canister accessible on the front engine bulkhead that is easily accessed from front of MH under the "hood"...
Might need to add fluid and bleed the brakes.
John Day....|'88 Winnebago Super Chief 27ft. Class A
Eastern .....|'88 KIT model 240 24 ft. 5er
Oregon ......|'02 Dodge/Cummins 2500 Quad Cab