This is a battle we are fighting at our park. We have both section of asphalt milling packed down like asphalt and gravel roads. The gravel road sections are by far easier for us to maintain.
Now to your question on how to fix potholes that keep coming back…
Prevention is always better
First, pot holes will happen over time. If water gets under the road surface and you have frost action it is inevitable no matter what the road surface is or how good of a road base you have.
Second, if you have a bad base for you road you will have pot holes. I’m basically talking about soil that is high in clay or is just muddy due to a high water table. Our park has high clay and we ended up putting down three inch septic rock (because it was what we could get in large stone at the time) and compacting it into the clay when it was water logged. Three inches at a time until the clay stopped eating the rock. It took six inches to stabilize the soil so that it could hold the weight of a car. We are going to wait a year and see if we need to do it next spring. At that point we will probably add road mix or asphalt millings for a more finished look.
Third, Drainage. If you have standing water the above two items will happen more frequently. The easy was to fix this, if your park in not is a low area, is to wait till it rains hard and have you maintenance guy take a hoe, shovel, pick etc and remove anything that is making water pool. You can also do this by leaving a hose run at the high point of the park and clear any blockages that cause the water to pools.
Fixing existing potholes
Get a couple yards of road mix delivered to your park and have you maintenance guy wheel barrel some to each hole in the spring or have a tractor with a rear blade regrade the road periodically. If your road is in overall good condition you should only have to do this once each spring. An added benefit of running a grader over it is it will reduce any wash boarding that happens over time.
Just in case you are not familiar with what road mix is or it is called something different in your section of the country. It is angular rock that is either 1.5” rock down to stone dust or .75” rock down to stone dust. The poorer the soil in your area the bigger the rock you will need. The reason for angular rock vs. round stone is round stone will not lock together. The reason for rock down to stone dust is again to aid is compaction into a flat solid surface. Down side is it is why gravel roads are dusty
For gravel roads in generally good condition you can run a vehicle over the filled potholes if you don’t have a plate compactor. If you are filling low muddy areas with bad road base use larger crushed rock and a plate compactor.
If you haven’t caught on I am the guy who gets stuck with this at our park. We are vertically integrated and have found that the price of snow removal, ditch digging for utilities to units, mowing, and road work it was worth it for us to get a small loader backhoe with a rear blade. We use a Kubota BX23 ~$25k new but depending on the depth of your water and sewer lines a larger unit might be better. We looked at the upfront cost over amortized over 15 years of use and compared to hiring out the work and it was a no brainer even after paying me for my extra time. We went with the smallest unit because it had the most bang for the buck.
For a more specific answer it would be great to see a picture of the road overall and a close up of the actual potholes. But untill then here are some generic answers.
I just thought of one more option for you… Gravel road mix is cheap. Delivered it should be ~$20-25 a yard/ton. For $400 you should be able to get ~20 yard delivered and dump spread. Think of it as 2" of fresh gravel over x length of road. Normal road traffic will pack it down. A little rake work after the dump truck leaves and you should be able to fill in any nasty potholes plus add more to your total road thickness which could help.