A lot of how and where you wire this in depends on how you want it to work and the way your van is already wired. While wiring directly to your battery is the easiest thing to do, unless the item your wiring draws a lot of current, I would try not to do so.
If you want to tap into your existing accessory circuit, using one of the piggy back fuse holders would work. Robot Check
That of course puts it on your starting battery, and would have power when driving or the key is accessory mode.
You can wire it into your house battery, but here again it would be better to tap into the Fuse distribution for your house battery rather then going directly to the battery . 10 Gauge seems excessively large for this device, but much of that would be determined on the overall circuit length.
Direct battery power connections can cause issues later on if you want to install battery disconnects, battery monitors, and such.