I don't mind camping in rain, dust or other dirty, messy weather. But I HATE it when all that gets dragged inside. Leaky tents, penthouses, or whatever are usually not the problem so much as the stuff you bring in on your coat, boots, etc. Tent designers at least got around to making every more generous vestibules so you could leave your boots outside, and a microfiber towel does wonders to get some water off your clothes, but it's still messy.
Vans are great so that you can get out of the bad weather, but have the same issue of bringing stuff in. An awning seemed like a good idea so that you could use the area outside the door as an open-air mud room, but often in the worst situations it's blowing too hard to use. I've used a small tarp that just fits over the open side doors (attach to rain gutter and just let it hang; when you open both doors they hold the tarp up enough to create a small shelter). But your feet can still be a mess.
It finally dawned on me to use a boot tray (yeah, duh). Got a couple at Target; see below. Work great. I sometimes put one on the ground outside so I can leave the shoes outside (and create habitat for scorp's
The other thing that has come in handy for messy conditions is a plain old fashioned burlap sack. Since they're used for erosion control they work similarly outside the van to stabilize mud or whatever. And since they're cheap, you can just toss them...and they're biodegradable. And they make nifty sandbags (and work somewhat better than carpet when filled and put under wheels for traction). And can be trashbags.
I've also been using a knitted polypro ground cloth like so many of the RVers have; for instance see:
http://www.amazon.com/CGear-Sand-Free-R ... d_sim_sg_2
They're pricey for the big RV versions, which is overkill for us, so look at the "sand mat" types that are smaller. It's like the fabric in shade cloth (which also works) or stuff used in outdoor chairs. The nice thing is that dust and water just drops through the weave, so it acts like a super-small grate. And you can just hose or power wash it off at the end of the trip. Way better than in impervious tarp.
I'm wondering what other ideas people have come up with for the mud room problem. I'm not a particularly finicky person, but I'm doing longer trips and I need to be a bit more on top of the problem before I turn the inside into a dump truck.