The concrete and septic tank companies sell a paver that is thicker than the standard paver you buy at the home store. They are a bit more expensive, but I determined I could get six for under $100. I don't remember the exact price, but I am just waiting to get someone to help me level and dig them in. I tried doing that with regular pavers and they weren't as perfectly level as I had hoped and they cracked when I backed onto them at an angle. I figure 4" will handle the weight much better. Otherwise I don't put anything on the ground under my trailer.
When I moved into this house, there had been gravel at the side and it was a real pain cutting grass where there was still gravel mixed in with the grass. As I don't plan in staying in the house for more than 4-5 years more, I don't see investing more money in the yard, that won't come back when I sell.