Can a person connect batteries from trailer to truck camper through the solar connection with jumper cables
Post this in the solar forum for more answers, but you should be able to connect as long as the polarity is correct. DC voltage doesn’t care if it’s from the sun or another battery.
You can if you want to melt the wires. If the battery in the trailer is severely discharged you could easily overload the tiny wires they connect up to these external solar connectors.