If you're in eastern NY - go visit Colonial Airstream and spend a day sitting in each model. Test the beds, the bathroom access and seating room and imagine being stuck inside for 3 or 4 rainy days. That will do more to clarify what you'll be happy with than anything else can. You don't want to make a mistake and then need to trade up or down.
Colonial does get a few used Airstreams in from time to time. I note that they have a Safari 27 FB SE in right now that might be your cuppa tea. Oh and if you get in the car now, you'll be there by the time they open tomorrow.
(written at 11:28 PM Friday)
You CAN get a 27 into most federal and state parks. And you still might be the smallest thing there.