Do I have to use expensive, vented battery boxes & vent tubes & vent caps....., to vent 2 batteries I want to mount in the cabinet of my popup, or could I use a vented access door like the one behind my 3-way fridge? It seems to me it would offer more ventilation than a vented battery box & I could line it with screen to keep out insects. I could replace the latch with a lockable one & this would give me access to charge even when closed down. I have to mount the two 27 batteries, I just impulsively bought (because of a sale), closer to the axle because I will be over my tongue weight limit if I mount them out front. I realize I still have to use regular battery boxes or trays inside to keep the batteries from bouncing around while traveling. I'm 90% sure I'm confident in doing this, but I'm also not an expert on venting batteries so I don't want to blow anything, myself or anyone else up!