One of the problems with solar and camping is that in camping weather you usually try to locate yourself into shade.
500 watts is not much power considering you won’t have them at their best angle but it is a whole lot more than nothing. That being said you need to realize that you will not get 500 watts except on very sunny days in cool to cold weather. You will never want to take your batteries past 50% of charge. You can if you are willing to get a short life from your batteries but if you intend them to last you will not.
It would be wise to get a camping refrigerator that uses both cycles, that is electric and propane. During the day when the refrigerator gets a lot of use use the battery electricity but at night use propane. The propane will be slow to recover but can hold temperatures just fine.
Your battery is rated at 20 hours but you should calculate everything based on 10 and subtract 10% off the top for losses. I wouldn’t count on more than about 10KW to get you down to 50%. If your refrigerator pulls 2000W then that gives you about 5 hours of run time without charging the batteries. The refrigerator will run a lot until it gets everything in it cool and then will only run about 25% of the time after that if you don’t leave the door open.
Since you have 500 watts and you could potentially have it 5 hours a day that 2500W total, with losses you should be able to just about keep up on your refrigerator without running a generator to charge the batteries. If you add lighting you will likely have to run a generator a couple hours each day.
If your refrigerator is 12V and your system is 12V you are more efficient and could get a little more than going through your inverter first. LED lighting is the only lighting you should consider, you will be able to do a lot with 20W.
You have enough to do what you want if you are careful, very careful. You must make sure your panels are at the best angle, never in the shade and that you get in and out of the frig quickly and don’t open unless you absolutely have to.
My expectation is that you will probably have to run the generator each day at least an hour or two to make sure you never go below 50% unless you don’t care about the life of the batteries. Most people are more concerned with having a good time than they are managing their electricity.
I picked up a small fridge/freezer at a thrift store for about $10, it's just a couple of cu. ft. I plugged it into a Kill-o-watt and let it run for 24hrs., simulating a typical usage by opening/closing a few times during the day, it netted about 30W/.71 kwH in that(temperature controlled environment)time period, 'course that wouldn't likely be the case on the road.
I'm sure going with 12V/propane would be the more efficient way to go.
Oh, and yeah, I realize there are quite a few factors that reduce actual power input/output for these type of setups. Mine is more of a project right now to get a general sense of how these things work, what I should(and shouldn't)expect from them as far as their usage/limitations.
....meaning at this time I have no plans on going for a full off-grid setup(on the homestead anyway), just trying to gain a little knowledge...not to mention preparing for a bug-out when the zombie apocalypse hits(should illiary be elected).