Welcome to the forum. I think you will generally find that the older the coach the harder it may be to get someone who is familiar with its specific details. Even owners of new coaches seem to receive generic owners manuals that only provide general coach information. Detailed chassis schematics are almost nil unless you go to a Ford support web site and pay for a short term access. Occasionally there will be someone who has the specifics you need and you lose nothing by asking for assistance. The other good thing is that coaches of successive years can be very similar in many respects so you may find what you need by searching similar coaches that are a few years newer than yours.
I am not familiar with your coach specifics, but typically many of the key AC breakers and DC converter fuses share a panel located at the foot of the bed or in the vicinity. If not there you will have to look for it.....unless someone can respond specifically for your coach.
Regarding your lighting issue you say only the front clearance lights donít work.......so light switch in park position turns on all rear running lights, but nothing up front (markers nor upper coach lamps light)? I would expect the +12VDC from the light switch in park position would likely feed both front and rear ccts off one fuse, so possibly a bad wiring connector in the dash or perhaps a bad common ground connection for the front lamps. You could try to use a multimeter and see if you are getting +12VDC at one or more of the problem front lamps with switch in park position......if +12VDC is there, then you can start looking for a bad common ground wire or connection as a start.