Thanks for all the encouraging responses! I am somewhat familiar with the area, from many visits and from going to college about 60 miles away. I do have a question: I am no longer very confident driving interstates, and I am hoping that I can get around the county and nearby counties without having to get on one of them - there seem to be a lot.
I just saw this today. Sorry to hear about the recent delays that may cause issues. I hope this works out. I expect the builder wants to finish before higher tariffs come about, because it gives them no advantage to wait and pass the cost on to you and they know they may lose some sales.
I would reconsider avoiding interstates on your drive. The speed may be scary, but it should be pretty consistent. I think your cat would find it easier than breaking and accelerating around stoplights. Newer cars have adaptive cruise control which make it so much easier to drive in traffic. If you have an older car and have been thinking to buy newer this would be a great time/excuse to do so.
The trip will be considerably faster on the interstate, which will be much easier on you and your cats. Once you get out of Jersey and eastern PA the traffic should be lighter and less aggressive. I tense up more on full access roads where cars may be pulling on or off the road at any time, and on a two lane where an oncoming car could be passing another car and rapidly approaching me in my lane, or an inattentive driver may be drifting into my lane. That drifting can happen on the interstate too but at least we are going the same direction. Time your trip to avoid rush hour in big cities. Driving on a weekend would be better than a weekday, just check for sporting events or other large events that can clog up traffic around a big city, race track, or college town. Use google maps or Waze to guide you around bottlenecks.
Trucks, yeah, not fun to deal with but this is really where adaptive cruise shines. If you're not in a big rush just let it slow you down as needed, and pass when you feel comfortable doing so. Blind spot detection in new cars help a lot with this.
Can you make it in one day? I don't know how many cat friendly hotels there are these days, and that can be upsetting to the cat as well. Take an hour or two practice ride on the highway with your cat and see if a sedative might be needed. Most of my cats have been yowlers but I took one on a few long drives and she settled down. My current cat doesn't make a peep nor seem stressed even on my winding hilly local roads to the vet.
Good luck with everything! If you have other issues that deter you from driving on interstates, feel free to disregard my suggestions.