If you are driving and your truck's charging system is connected through to the RV's batteries, they should fully recharge in a couple hours or so. If you are not driving, then a generator should recharge your batteries off the RV's charging system on AC just as quickly as it would plugged into any other AC source.
I can recommend you first get some decent gauges to read how your batteries are being used. A good volt meter and amp meter, preferably built in to the RV via a display panel would be best. I do that with volts but for amps I have a clamp-on amp meter. For example, I know my heater draws 4.7 amps to run the blower fan. When the air temps outside drop below freezing, it runs about 15 minutes on/15 minutes off all night long; call it 10 hours, so 5 hours @4.7amps equals 23.5Ah. All your other loads are inconsequential unless that AC inverter to run the TV is a real power hog. I bought a 12 volt powered LED TV and it uses 1.7amps at 12 volts. It's only a 17" screen, but still, not much power to watch a DVD movie. If I were to guess, I'd say you probably have a load over 24 hours in the range of 35Ah. Even if it was 50Ah, you should be able to go 2 full days before you really needed to charge that battery.
As someone already mentioned, you'd be a great candidate for solar. I have 250 watts of solar on the roof running through a Morningstar charge controller that displays volts as well as both charge and load amps. I know how much load I have at all times as well as how much my solar is charging my batteries. Rare is the day that my solar doesn't charge up my batteries to full by noon. I get a real 9amps of solar charging for at least 5 hours a day and a total for a full day that is sunny, about 70Ah. I've dry camped for many days in a row in the winter well below freezing and only once did I need to charge my batteries. A great thing abou solar is that your batteries are always kept charged when the RV is not in use and never needs to be plugged in when in storage.
I also see someone recommended you check the electrolyte levels on your batteries. I agree. Many times batteries leave the factory unable to meet their label specs. It's not the end-all to tell you capacity of the battery, but it will tell you if it's fully charged. Only a load test will give you capacity. If you want to run a load test, you should be able to using any of your on-board loads, measuring the amps draw against time and reading specific gravity on the battery's cells.
It's also important to check electrolyte levels fairly frequently on wet cell batteries. I have one of those set ups that replace the battery caps with a plumbed system that allows me to refill the batteries remotely. Use only distilled water. I'd say I go through a gallon of water a year, checking once a month.
