GFCI outlets are typically those located near a water source such as kitchen sink, bathroom vanity, etc. I would not expect those at the front of the trailer to be on a GFCI protected circuit.
A couple of things to try as a start. If you are comfortable using a voltmeter on live circuits. Check to see that you have 120 vac on each circuit breaker, even though you have previously reset all of them and they appear to be ok. A bad breaker is not likely but possible.
If you do have 120 vac on all of the breakers, then try a non contact voltage detector at each of those outlets. It is possible you have voltage to them, but no neutral.
Having 120 vac at the breaker, but no voltage at the outlet indicates a loose hot connection between the breaker and the first outlet in the string.
Having hot at the outlets but the outlets not working would indicate a loose neutral wire connection between the neutral bus bar and the first outlet in the string.
It is going to be a process of elimination of the possibilities.
https://www.homedepot.com/p/Klein-To...E&gclsrc=aw.ds
Or use an outlet tester for even quicker test.
https://www.homedepot.com/p/Receptac...B&gclsrc=aw.ds