Well OP,
I came into this late but, here's my take on your situation. First, I have no idea on what a "support bar" is. Second, I doubt Bennington built your (and any similar models) AROUND your batteries so they can't be accessed. Sooo, I suspect that you may have to remove that support bar to gain good access to them. And third, here's what I did on our '14 Benny 25RCL for trickle charging and maintaining. I gained access to my dual batteries simply by removing a rear tail gate that hides them. But, that's our boat and the way it was built. Then, I added/installed what's called an *SAE* plug to an exterior panel right next to the tailgate. That plug goes to both batteries.
The plug is secured to the panel via 10-24 stainless steel screws and lock nuts. And, there's a weatherproof cap on that plug for when it's not in use. After that, I can simply walk up to the back of the boat and insert the opposite end of the plug from my 4A smart charger. It takes about 3 seconds to hook that charger up and walk away. The batteries are now maintained and are kept topped off. I have had ZERO worries in 3 years since I installed that plug and use it for maintaining the batteries.
Scott