So, after I got the working board I get some generic USB C “all in one” no name breakouts / docks to get the signals out. I am brain storming on all the parts I need, which means a lot of time consuming browsing on the “usual suspects” in regards of websites. Currently I bought a lot of nice momentary push buttons and a big emergency cut off (this will not be in line for the motherboard, just for the power going to be feed to the payload 
).
Also I was thinking about the kind of water tight case I want to build everything into and might have identified a possible case - however, this one will come last. I frist want to get all other parts, losely assemble and see if I can squeeze anything into the needed space. Yeah, space will be a premium and people with more lu… tim… experience in CAD might draw this all beforehand… I have a more… practical approach to those things :D.
Regarding of seeing things: Monitor. Important. Should be high resolution. I actually wanted a touch screen, but might choose other possibilities. The guides here in forum ( Unofficial Guide to Aftermarket LCD Replacement , HDMI controller board for display panel , Matte screen please! :) ) hyped me up to get the panel and go that route - so I will see if I ever come to adding a generic touch panel with 13.5 inch above it - but @nrp @John_Perez and @Matt_Harris have already been incredible helpful with documenting their works, so its just awesome to tap into all these resources - thanks a million guys! 