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.