Going "in" may cause some pitching effects due to the increased pressure under the elevators. Who knows, the pitch down that may cause could eliminate the possible pitch up effect of the slanted rudder hinge line. Flight test will confirm this. My prediction, you can't move the rudders enough to really make a significant drag increase. Kind of like flaps, 10 degrees of flap hardly changes the drag, 40 degrees causes a big increase.

I have flown my BC without the gear doors. The yawing oscillations were eliminated, but I'm glad I was on the lakebed when I did it. The model just wouldn't slow down, and that was with the idle thrust of a 500.