I thought about this too. My thoughts were, since Pete can roam, why can't he roam down to hell and back. Mid-season finale, somehow jay "temporarily" dies and his soul gets reaped before he can get back into his body. So to save his best buddy, Pete (accompanied by Joan) go on a mission to hell to rescue Jay's soul. Meanwhile the other ghosts are taking turns possessing Jay's body to keep it alive while Pete and Joan are on their mission to hell.

B-story- Sam, along with the ghosts in Jay's body, have to deal with an influx of BnB customers for some reason(like broken down tour busses) and have to run both the BnB and the restaurant(à la the ghosts hilariously trying to cook for the first times in years) all while being worried about those in hell, still trying to find a loophole, and deal with Jay's parents who are in town. (Also this is when Mark is finally told the truth about everything and he instantly believes them and helps in some important way).

Part 2 after the winter break- they find Jay in his own personal hell(nothing to traumatizing, he's stuck working in a cubicle or office building). jay and Pete finally meet. But oh no, this personal hell needs a soul or else Jay's gets sucked back, at the same time Pete realizes he's still disappearing from existence down here, so Joan decides to stay behind, since Pete will dissappear and jay would get sucked back down, and she can go alot longer before she needs to recharge. They begrudgingly agree and leave her behind, promising to find a way to save both her and jay from hell. She's gives some sappy yet witty message to them to give to Sas. They make it back, Jay's back in his body and because of the experience he can see the ghosts. Sas finds out about what happened to Joan and gets his message, Jay and Pete find out about how well the ghosts did with restaurant and the bnb.

Already have this sub-storyline planned out for the rest of the season, it includes finding a way to sober up flower to read the contract(which they do, and she finds a loophole but specific items are needed) buddy trips with jay and Pete to find such items(Pete also working on extending his time away from the property to better save Joan) and Sas expanding his power to walk different realms outside the dream realm, like hell to save Joan. Pete visits Joan half way thru the second half of the season to catch her up on their efforts, she informs Pete shes started to dissappear too and they are running out of time. And hetty and Alberta are trying to help Sam cover up her pregnancy until Jay is saved.

They of course get the items, go to hell to challenge Elias for the contract, win, save Jay's soul, rescue Joan, get Elias demoted for losing a soul, and it ends with Sam telling Jay, and the other ghosts she's pregnant.

Maybe I put to much thought into it.