Weather, Weather, Weather! At least this time of year in that kind of plane. Your Commercial & Military training may help, but sort of like a GA pilot looking to move up to the Airlines... It sort of helps, but they tell you to forget what you learned. Any situations you had in the past you probably had an "out" for in the planes you fly. But, now you're in a little Cheetah.
If everything is in your favor, you may have a big High starting in the west and slowly moving east that you can just follow, but unlikely. I've made 8 or so X-US flights in my Mooney (so 16 times if you separate the out and back) and granted in the summer, it can be pretty uneventful if you don't have Wx to contend with. And I'll assume the plane is IFR capable, but this time of year you can get grounded by broken clouds that you just shouldn't climb through. I once did an Oct flight where almost every flight was CAVU, but I still managed to log .2 because out of KAWO (north of SEA) Departure made me climb to the West vs just heading South. Had that been this time of year, I probably would not have been able to do it due icing. Besides that factor, here's my list:
Many of your fuel stops will probably be into smaller airports, NOT the kind you're use to. Before you depart, CALL AHEAD to the next airport just to confirm there are no issues with the pumps or anything else.
When you call these smaller airports, ask about accommodations. The FBOs at these 3-4,000ft runway airports also often have deals with some of the local Hotel/Motels and they even have a deal where they'll come get you and bring you back. Worth knowing, just in case you can't depart due to what's further down you route. If the FBO doesn't have any deals, just do a quick search the night before about potential places to stay at your different stops the next day.
Ah yes, the Crew Car... A lot of these smaller airports may have a loaner/crew car, but then they may not. So worth checking into. Also... at the bigger airports you're also probably going to go into, remember you're not flying your big metal $$$ aircraft. So the FBO may be hesitant to let you have a crew car if they have someone else coming in that's going to take a lot more than you're 20 some gallons.
For your schedule and mental health, schedule at least double the number of days you think it will take you to get to PA. Wx could stop you for day or two, you get going and then you end up somewhere stopped again for a couple of days. If it all goes well and it takes just the basic number of days, great. But don't get into a get-there-itis situation.
Get it in your head the plane you're flying will not do ANYTHING the planes you're use to fly will do. There will be a point you can't climb above something, you can't descend through something, no deicing and the prop can ice up just as fast as the wing in moist air. And I'm assuming you're already going to be fully loaded, so your climb rate is going to be pretty bad.
Down low there's a chance you are going to loose ATC every so often, which is something that probably doesn't happen to you much. No biggie, just reach out and see if anyone can hear you on the Freq that can relay to ATC. Then just find out what the next Freq for you will be and when you'll be in range. Common sense yes, but it might not be your first go-to action the first time it happens since it just doesn't happen on your normal flight. I usually fly in the 15/16K range and through the Dakotas and Montana I've had some dead spots. And more than once I've been asked to try and reach someone down low by me to relay a message. (Again, maybe not such a big deal down south.)
Keep us posted on your trip. Should get you back to your roots of stick & rudder.
