Overall I like your analysis, and as a long time (28 year season ticket holder, thats rare to agree with other people assessments of the Jets.
First, UNLESS, they totally love , and I mean toally love one of the QBs coming out , I would avoid drafting one until at least the 3rd or 4th round at best. I would do as suggested , let Petty, or preferably Hackenburg play. I would sign or trade for a journeyman, just for an extra QB body in case of injuries. 9McNown or Glennon ?)
Also, and I take this idea from my son who is 21. I would cut any player that you dont think is in the plans for 2018. No sense giving reps in practice or time in games to guys that wont be there. That means Im cutting Revis, Marshall, Mangold, D HArris (unless you want him to groom a young MLB) Decker, Skrine, and yes even Forte (Powell is a very capapble back to start or have in tandem with a young RB) Aside from giving young players reps, there would be substantial cap saving, and if any of it is dead money, so be it..get everything clean and off the books for 2018.(already done with Breno and Folk)
With Free agents..I would sign young hungry guys, looking to make a name for themselves, noone thats getting their third contract..
with this if (or when) they suck in 2017..young guys can get experience, you will have a more definitive answer at QB, and could also set yourself up for Darnold or Rosen in 18.