There should be an access panel close enough to remove the plumbing and faucet for repairs depending on the floor plan. You say there is a cabinet adjacent; look there for a panel with screws that can be removed.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7