Gettysburg will be packed with the 150th anniversary of the battle. We were up there last weekend and the crowds were already building. If you decide to go in the other direction we used to camp in the smokies for the 4th and there were several options for fireworks.
We have boondocked and just filled a gallon jug to flush the toilet. After you go and push the pedal just pour about a cup or so of water in the toilet for next time and to keep the seal wet. We have done the same thing when traveling in the winter and just used RV antifreeze.
I would try the bunk ends first before you seal it up. The whole point of having a hybrid is the extra space gained by having the pop outs. We recently turtled and it wasn't to bad for a night or two but would switch to a TT if it was permanently sealed.
I saw one at an RV Show in September and it was pretty nice. The outside was almost a bronze color and not the typical white. The inside was very spacious but I am not to sure there was much more storage than the 23SS since we have a Roo19. We did go back and look at it a second time before we left since we were so impressed.