Feel your pain. I stayed on my friends property in Florida and within a month my carpet was shot. I could sweep/vacumm 10 times a day and couldn't keep the sugar sand laced with dirt out of my MH!
I DID find a certain type of mat that has
high brown bristles on it. Usually sold with a design of some sort on it black ink.
THAT mat will grab most of the sugar sand off your shoes and off dogs paws. Cut the amount of sand that got tracked in in half.
They look like this and really work just walking on it grabs the sand off your shoes. Buy the one that has
long brown bristles NOT the smooth ones, they don't work with a darn.
Only other way is to take your shoes off before you go in the RV which sucks because you have to leave them on the ground outside the steps. And then do a balancing act to get them back on when you go out.:R
Which brings me to another learning curve about RV'ing in the southern states. Left a nice pair of leather shoes outside and in the morning was covered in dew and ruined. Welcome to the South sand and humidity and dewy mornings. :(