Hi,
My first set of Trojan batteries lasted 13 years. You might as well try to get another 3-5 years out of yours.
As for the 100 watt panel, it will help more than not having one at all. However the CO meter, propane detector, and refrigerator will use about 35 amp hours daily, or about what the 100 watt panel will recharge in about a day of good sunlight. So your 220 amp hour batteries would last about 4 days without the solar panel, and close to a week with it. A little time charging with a generator, or some sightseeing in the truck will also top off the battery when solar is there.
Fred.
