Totally get the mud struggle. What worked for me was using heavy duty trash bags over my shoes, which sounds silly but was a GAME CHANGER. No more wet socks or ruined pants since I just toss the bags after. Having backup clothes in the car is a great idea, and I do that too. Once you stop fighting the mud, the whole thing gets way more fun.

Heat-resistant meals" sounds like something you'd pack for a trip to the sun. You might have to accept that anything you bring is just gonna get cooked a second time, maybe even a third. I'd say just embrace the hot lunch life and bring stuff that's meant to be served warm, like a thermos of chili. Or start eating cold beans straight from the can like a true champ.