We have two batteries on our 2013 Trail Runner, so no room for that.
However, we do have the slide-out rear bumper bike rack . . . but it is such a PITA to put the bikes on that rack that we hardly ever take the bikes with us, and we've found we don't take them off since it is such a PITA to put them back on!
It's much easier to throw the bikes in the back of the truck . . .
So, I now have a large Rubbermaid Tub that fits perfectly on the bumper rack that we carry our firewood in and I strap it down with ratchet straps while on the road.
Sorry . . . don't have any photos.
I could pose one tomorrow!