Solar panel drop in input power with connections

I did use the search function, and scrolled down a couple times, did not find exact topic.

I’m not a solar expert, just been using portable solar panels (100w and 200w), into my jackery (300, 500 and 1500). Mainly for weekend camping and hunting trips, never more than 4-5 days but mostly weekends. I was running 100w foldable panel cable directly into my jackery 300 and 500, and getting about 70 percent input with optimal sun.

I recently picked up a GFC camper and wanted a direct plug into the front cab wall, instead of running cables under the hinged panels or through a back window to charge my jackery batteries. With the GFC, I was thinking of drilling the hole and using an SAE connector plug, with an SAE to 8 mm extension in the bed, to plug into the Jackery. I just got the cables and tested it. From the panel, the 8mm plug goes into SAE plug into connector that would be mounted on exterior of GFC. On inside, the SAE extension cable goes about 8-10’ and has 8 mm male plug to go into Jackery. I’m now getting about 30-35 awh input. I anticipated some power loss with the plugs and length of cable. Is this typical and is there a better cable/plug option? I am now just thinking of drilling the hole and using a rubber grommet, as I had initially planned, and going straight from panel into jackery. When not in use, I’d make a plug for the hole.

Thoughts from the brain trust here? Pics of the SAE plug/cables and the other grommets I have picked up. As of now, no holes drilled…yet.