using jumper cable from your truck to the trailers batteries will work but over the long run will be expensive in gas and wear and tear on the truck. (not to mention leaving your truck running for hours in the city.)
I can make a 250w range solar setup for around $500 each. I use two while camping for up to 34a of charging whenever the sun is out. Then again I use them out in the middle of no where and they don't grow legs. Installing them will cost some and make them safer but you will lose some of the power because they can't track the sun.
A small Champion 2000w inverter generator would be as quiet as any and cost around $500. With it you could charge when needed and use much less gas than the truck would. Even with solar you need a means of charging when the sun doesn't play well so getting the generator first may be prudent.