Hi Van Der Graaf !
Welcome to Subsim !
I am happy if my tutorial was able to help you :-)
Your mods list is very nice !
You are right : full interior + opti ARB widegui (or another widegui) eats too much ram.
Black sea Campaign is smaller (costs less of RAM) but in more Hansolo had to reduce animations in the interior of the type II (in particular motor engines). So it works together with Opti ARB widegui !
In the pleasure !
Eric