John
I used pneumatic pistons for main gear doors and small servos on the nose gear doors, On #2 I plan on using servos on all doors,BTW I use the wind to close the large door on nose door . Your right on the wing tubes they are heavy(UG) & keeping the wing Center section with nacelles & fuselage is what I did and it rolls into my avalanche, so I only have the flaps & aileron connections on both outer wing panels,No air lines .
On #1 I put the batteries in the nacelle 2 X 4 lipos ,yes its might be a pain removing the props and nacelles to replace the batteries ,but the a/c need as much weight forward to achive the CG without adding lead.
Semper Fi
joe