WELCOME and HAPPY NEW YEAR!!
You and your brother in law should have NO PROBLEMS getting 12-14 hour burns at 450f or so out of a Chubby. Heck I did that for 2 years with a Chubby Jr. I am getting 14 to 18 hour burns now with the proto Chubby so a long extended burn time isn't a problem for these stoves.
The biggest obstacle I see from what you posted is the house itself isn't insulated very well. How big is the house? I am sure I am not the only one who like to see some pics of a barn converted into a viable living space!
There are alot of good solid stoves out there to choose from and this forum has a plethora of first hand information on them amd people on this forum are the BEST.
Don't be shy.. Any questions just ask!