Propane heater will kill you. Personally for resale (if you ever sell the boat), I would reinstall the aircon but no genset. Do as the capt says and run a battery bank.
http://www.surplusunlimited.com/Last time I was there, they had a few complete marine air/heatpump units in good shape for under $1000.
Heck, you can pick up a brand new MarinAire Micra 7000btu unit for $1200 that draws 110v/650w/6a (max). If 7000btu is enough heat for the cabin of your 268... two 400Ah 6v batteries wired in series gives you 12v 400ah of power. Discharge to a safe 50%... you have 200ah of usable power.
200ah of power can run that MarineAire Micra, with inverter loss... easily for 24hrs of constant use! Throw on a good solar charger on the roof/charge it with the boat while it's running.. could easily have a weeks worth of heat/ac before you need to recharge on shore power.
OR
Add a 2nd "charger" alternator on the engine.... charge the deep cycle's off that very fast. Never worry about a generator ever again. Those are old technology

You can even get fancy and buy battery "health" monitoring systems with relays that will shut off the aircon/battery bank if they dip below "safe" level to avoid damage, and also give you a real time runtime meter. All this stuff is very inexpensive. Minus the labor you're looking at around $2000 for everything and it gives you more power to run the TV when the boat is off too.