Soft & sometimes soggy ground

I don't know about trailer leveling, but I had a problem leveling my motorhome on a muddy campsite. As I extended my front two jacks (left and right), they just kept sinking...even with wood blocks under each of them. A nice fellow camper brought me a long piece of wood about the width of my motorhome. We laid that down under the jacks so both would extend onto the same long piece of wood. That worked much better. I just left the wood there for the next camper.