1) As always, Alpine is a good looking coach.
2) Pic1, re: close positive- Looks like they installed a dielectric spacer to get the nutting plane above the surface of the frame member. You could easily add an insulating washer, ~3" diameter, to avoid accidental shorting to the frame when doing maintenance, on top of the dielectric spacer/below the positive wire lugs. Could be homemade from any durable plastic sheet. CW has some 1/32" cutting board sheets that would work nice.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project