Re:
Splashbacks, since the mud/clay/gloop/thorns just stick to the tyres this side of the Humber. A small amount of skill and you can ride anything with them.
On the rare event we go to the wrong side of the Humber, then nobby nics will be fine, which have been fine for pretty much everywhere, peaks, moors, lakes, bits inbetween and still rolling fine after many years. No idea what this newer style Nobby nics are like, but shouldn't be too much different.
The only other tyre is a smoke lite as it cuts trough the gloop an is narrow enough to get to the harder gloop under it and then grip.
Nothing stops the buildup of twigs, leaves, shrubbery or stops the hawthorn.