I had this issue a few years ago, and fixed it by basically recreating a bike wash like you see at most trail centres.
Luckily I’ve space etc.
Levelled off a section with (tall) walls on two sides (an ‘L’), put a drain in that connects to our soakaways, sand & cement base with (slightly angled) pavers on top and fenced the walls with treated timber (looks like a fence). Also ensured that the majoirty of the mud etc doesn’t get in the soakaways using a ‘filter’.
I also brought water in (a bit more involved, 10 metre trench and a blue pipe from the nearest outside supply).
An Isambard* as my OH would say.
And if I knew how to post pics, I would…
* – why use a 2×2 when a 4×4 also does the job