Just like cats have whiskers to help them know how much room they need to get through a space, you'll develop a feel for where you can fit.
I drive a 3500 dually and I can fit into just about any parking structure and most parking spaces. My tail will hang out the end, but I'll fit between the lines every time.
Just get out and drive it (and park it) and get some experience. It shouldn't be any big deal compared to the Class A you used to drive. Plus you've got a duty to uphold the tradition of "Everything's Bigger in TX".