I dug up a link to the Mac SE/ARM to show you an example of a "stealth" mod. He also has a homemade and open sourced graphics engine driving the original CRT & AB, which might be of interest - though it's not attached to anything remotely resembling a normal Mac/VGA analogue video output.

About half-way down this page, he shows his method of creating a stealth set of rear ports.

Here's a hint