that block head screw is a standard type of screw in RVs.
mine was also behind a similar panel. i ended up putting a hinge and making a door out of it.
Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package