Riding without a rear guard is for loners.
Nowt worse than following someone in the wet without guards.
Off road I’d go for rear guard, crud catcher and one of those you fit on the forks to stop spray into face. As for the ‘they don’t fit with dropper posts ‘ etc. Can someone please explain why you would need a dropper post if your bike fits you correctly ? Been riding mountain bikes for over 25 years and think I’ve only felt the need to lower my seatpost once (descending Rangers path, Snowdon)
On the commute its full SKS on the touring bike, keeps me and the bike clean and a lot drier than without – which is important as my commute involves a 35 min train journey in the middle, and I sometimes cycle to meetings etc.
It’s also harder to spot/avoid dog sh## in the wet and gloop. It might just be me, but I think you look a bigger t#t with poop on your clothes/face than guards on your bike.