Since you've indicated he may have had money stashed away, the foul play would work if he was accessing the funds from Lewisburg. Or even I suppose if he and said lover got to Vermont and slid across the border. Which might account for a body never being discovered.
Snipping just to use as a reference.
I have better foul play scenario:
RFG could have been involved another woman. She could have been married, a defendant, witness, or a close relation to a defendant. Somehow, he became involved, leading to his distraction from mid March.
On 4/15, he was going to spend the weekend with her, outside of Lewisburg, possibly a vacation cottage/cabin type place, secluded. He will meet her for supper. Lewisburg is out of the J/A/SC media market, so it is unlikely he will run into anyone he would know.
RFG wanted, for a long time, to get the data off the laptop. He was going to drop it in Raystown Lake, but he ran into someone who knew him. He thought he would drop it in the Susquehanna. So, on 4/15/05, RFG gets to Lewisburg, around noon. He removes the drive, perhaps after using cleaning software on it, and tosses it. He can take care of getting rid of the laptop and is romantic encounter on the same day.
Later in the day, she shows up and before dinner, they take a stroll through the SoS, where at least two witnesses see them. They eat, go to the cottage, in her car, and spend the night. Using her car explains why there is no scent of RFG outside of lot. She is a smoker and leaned into the Mimi, getting the smoke into the Mini.
The next morning, they go out, possibly for lunch or for her to buy something. RFG checks the Mini and waits for her.
They go back to the cottage.
Sometime that night, one of two things happens:
A. They get into a heated argument and in a fit of rage, and possibly without intent, she kills RFG. (2nd degree murder or possibly voluntary manslaughter.)
B. RFG has a health crisis, he has a massive heart attack, or an accident, e.g. he slips in the shower and breaks his neck. (This includes a Nelson Rockefeller scenario.)
In either event, the woman, who could be married or with some shady ties, or both, may not want to explain why there is a dead DA in her cottage. It is remote, so she can hide the body, possibly burying it. That would be the crime of Abuse of Corpse.
This would be the most likely murder scenario, but there are some problems:
1. Mel Wiley would have to be a coincidence.
2.
20/20 Vision would have to be a coincidence.
3. The bank account would have to be a coincidence; so would putting the Mini Cooper in PEF's name.
4. Disposing of the laptop would have to be a coincidence; he just happened to do it on the weekend he died.
5. Calling PEF from the Brush Valley would have to be a coincidence; it led the searchers to initially look at Route 192.
I would add that the change in demeanor is a bit weak as well.
This is probably the strongest murder scenario there is, though RFG could have been murdered at some point after walking away.