Any insight on how to get the wires from the Bluetti to the MC4 connections on the roof of my van without cutting the wires? What roof penetration would work best? Cut a hole and feed Anderson end down? Buy open ended MC4 and somehow safely terminate to Bluetti? Sounds like adding Anderson terminations can be tricky.
The cleanest way is to buy or cut off the MC4 connectors, feed the wires through a small hole and then crimp on new connectors. It is actually very easy to work with MC4 connectors. Just buy about triple the qty you need so you can throw away the first couple of tries if needed. Watch some youtube videos on MC4 connector installation for a good idea on what to do. Something like this will give you all the tools and connectors you need.
Here are two examples of entry points for cables that work well.