There is usually some sort of jurisdiction responsible for providing care. In those 'thousands of acres' you refer to, are they park lands? State, Federal or County Park? Is it National Forest? State Timber Lands, NA Reserve? If you find out who owns the land, you will find out who provides emergency response to those areas.
In our area, we have a lot of wilderness maintained and supported by the National Park system. EMS is primarily park rangers some of whom have EMT-B, some have Wilderness EMT. Some are state certified, some are NREMT. They do not see a lot of calls and some can get very rusty in their skills. I have also worked with some who are top notch.
Depending on the event and the proximity to response agencies, different protcols are in place. In some cases the park personnel will extricate the pt if needed and transport to a trailhead or nearest access road and hand off to local county response agencies. If injuries are severe enough, the pt may be airlifted from the wilderness site directly to the Trauma Center.
Around here, wilderness response does not transport. Our county SAR group is strictly volunteer (We run about 12-20 calls per year). Our only method of transport is in a stokes, on a wheel, pushed by people. We stabilize a pt, carry them to the nearest access road where the EMS agency responsible for that area picks them up.
Some wilderness areas have commercial resorts, ski facilities etc and provide EMS for their guests. Those EMS providers are the employees of those commercial facilities. Some forestry services will hire an onsite EMS person because it can lower their liability insurance and L&I rates. We also have some Dept of Corrections facilities that run forestry, wildfire crews from an honor camp that is located waaaaay out in the boonies. They have their own systems.
Do your research and see who provides support in those areas and what the career opportunities are.