I would guess that once you drive a few hundred miles you're going to feel like a pro. If I have a correct picture in my mind of your Winnie, keep in mind that the front is narrower than the living portion so if you think you can fit into a space by eyeing it for the front cab portion only, you're going to scrape something in the rear because it's wider. Don't ask me how I know. We rented one about 30 years ago for a family trip.
Fuel stations? Just allow more room when maneuvering around the pumps or choose an end one but always keep you eye open for an easy out.
No towed? I think you'll find that having a towed vehicle makes a long stay so much simpler and you'll get to sitesee a lot more. Unhooking all your connections to go somewhere gets old.
Have a good trip. You'll do just fine!