Wish I would have thought of the tri-stock on the trailing edges of wing-very good idea,will look better too. This will help get more throw to the spoilerons(spoilerons is when both ailerons are up).If you dont do 3-D,you could leave this step out,you only need it for harriers & elevators. Sounds like you got the vertical tri stock where it should be and the right idea for the blocks too. I doubt the t-nuts will come out without the hardwood block attached,I know this from experience(happened to both planes,I just glued that back on since the break was clean.If you have the slots big enough to fit the giant hinges in,I guess you might as well use them now,just get them in far enough so the hinge gap is minimal-so you can just see some light thru them up to about 1/16".Use an X-acto blade to cut out a pocket just for the hinge pivot point which is too thick to fit into the slot,that should do it. I always glue the hinges into the control surface first,then the next night test fit them to the wing,stab or fin.Sometimes additional widening of the slots becomes necessary due to slight offsetting of hinges.I use Pacer hinge glue,a water base glue,it held a 1/4 scale Su26 with OS1.60 together for 10 years,no hinge ever even came loose on that model so I can safely say its good enough for a Do.If you have a very loose fitting hinge,go with the Gorilla! Dont let any glue set up on the hinge pivot point,a little oil or grease there before glueing helps.