I have the same size and type of trailer, and park on second hand stall mats I found on craigslist. The seller gave me a deal to take the whole batch (boarding barn replaced mats in some stalls*), so I have a bit extra all the way underneath and extending out from under my trailer (including under the gooseneck nose).
Don’t have to do an incredibly precise parking job, either – just a decent one – and really helps with keeping the grass and weeds down around the trailer, making mowing that much easier. Definitely recommend the mats when keeping a trailer on grass, a complete set if possible.
*although they were already clean (no obvious manure or dirt), I scrubbed and disinfected these mats thoroughly after getting them home, since they were used