In Every RV I have been in including some that qualified for "Historic Vehicle" registratrion it's been breakers on the 120 volt side of life. Every one. No fuses, just breakers.. Have not seen Fuses used in new construction since I can't remember when. Possibly 1970 but I think it was older than that.
Now: GFCI.. All RV's have at least one.. Usually in the "head" (Bathroom) some have 2 or 3, I have one now will have 2 when I get round 2 it (Have 2nd, just not yet installed)
Screws loose.. Many RVers have a few screws loose... On my Rig when it was NEW and I mean NEW I had issues with the Air Conditioners.. Turns out the screws that clam the wires in the Power Distribution Center (Breaker box)>.. Well some of them I do not thing they even tried to tighten them at the factory THREE FULL TURNS and then some before they were tight. And in a couple other places as well.
Those are my suggestinons
Breakers
GFCI (2nd one hidden somewhere)
Screws loose.
Oh, and on edit an after thought.
RV's (And in fact many buildings) are generally wired like this
Breaker box=====Outlet 1=====Outlet 2====~~-==Outlet N
Sometimes there can be 4 or 5 or more outlets all daisy chained
Plug a Space heater into say Outlet 3 and the el-crapo Quick Box punch down connetion in Outrlet 1 or 2 (or 3) can burn out taking everything down-line off line.