So what I came up with was the wiring prep kit 82216274AC, which ramtrucks says is for VP2 or VP4 radios, but also says will not fit my vehicle. I've found the site is wrong about a lot of things, so I take it with a grain of salt. Installation instructions is here:
https://s3.amazonaws.com/rp-part-images/assets/f8e6cb0cde0215b57114112dbb4ee41c.PDF
And the trailer camera looks to be part# 82216068AD, which you can use one or two of.
Check those part numbers out with the dealer, and maybe double-check with the Ram tech people, because my dealer didn't seem to understand it. And prepare your wallet for a $2K bite plus labor.
Which is why I'm leaning toward alternatives.