Clayton,
The HobbyTownUSA at 3401 W. Greenway Road has half-a-city-block of parking lot. You could park a fleet of semis there! And, it's where we'll be holding Desert Scale Classic on April 11. Slip over for that, if you get a chance.
Actually all the shops Jon mentioned have room for semi parking, but HTU on Greenway has more than all the rest combined. Plus, you can do a little indoor kart racing, R/C racing, slot car racing, or slot drag racing while you're there!
Have a safe trip, and c'mon over!!