Welcome to the Forum.
I have no experience with the Adventure TCs, but can say it is worth while to take a backup tank of propane if you will be in the outback. As stated, with the adapter you can use the small cylinders.
I am not aware of any gauges for propane that you can count on. The pressure will change depending on the temperature. With the pressure gauge, it will show pressure, and just as soon as the tank empties it shows zero. It does not show the amount of propane. Residential tanks have a float that measures the level of the propane. Weight is the only other way to accurately measure propane. If you do not want to carry an extra 5 gallon tank, there are 2 gallon tanks available.
A Honda 2000 generator will run a small heater, probably about 8 to 10 hours without an extended fuel setup. It can also have many other uses depending on your camping style.
Wayne