GMRS Repeater Usage in Overlanding/Camping/4X4

I am trying to learn more about the need for (and access to) GMRS repeaters when camping and driving.

Understanding that there are many repeaters out there, does it make any sense to plan my communications and seek repeater usage if I am traveling across the country?

If I do not have repeater access but have a 25+ watt GMRS radio in my truck, am I going to have enough reach to find others if I am out? I know it depends on the location, but ‘generally’ if I am in a state park or similar?

Or, are GMRS repeaters only used by those with systems and base stations set up in more formal HAM opertations?

Thanks in advance!