If the cabover was rebuilt, then you are a lucky man.
If it is built on a Ford or Chevy platform, then any local shop should be able to do, tune-ups, lube, etc.
Important things to realize.
The A/C won't run without 120V power and pulls about 2400 watts. The microwave is also 120V.
Refrigerators cost upwards of $1500 and do go bad over time. Exercise yours on all three power options to keep it healthy.
Tires are always a concern. Replace MH tires every 7 years and L/T tires every 5, even if they have tons of tread. It's the sidewall cracks that cause the blowouts.
Your onboard inverter is only half your power controls. There is probably a second fuse box somewhere. Be sure you know where ALL your fuses and breakers live.
You have a battery SEPARATOR config. That means when you run the engine it charges both coach and chassis (engine) batteries, but when you plug into shore power it ONLY charges the coach battery. The chassis battery charges separately. When you store it, you have to connect two separate trickle chargers to keep each battery charged. If you want to simplify and increase reliability, you can upgrade to a modern battery COMBINER setup for about $150 (even less if you shop well).
Good luck finding the original manuals.
Jose