I'm in the beginning stages of making a simple pigtail to be able to keep my house batteries topped off with a battery tender. My 2017 Prism is equipped with the Furrion Solar Ready receptacle. The first step was to source the special Furrion plug. I got one on eBay from CNLINKO for $12.66. it is their part no. 20-C02PE-01-001. See pic for more details.
This same plug is the one you'll need to tie a non-Furrion solar controller to your rig.
Next up, I'll splice in a battery tender pigtail and get it soldered and sealed up.
TBC