I am going to use Koverall or some type of fabric. Just haven't decided yet. As far as the tank box. If I mount the fire wall flat to the front of the fuselage the two square cut outs in the fuselage former and the firewall won't allow the box to butt flat againt the back of the firewall. The two cut outs are inline with each other. I just checked the plans and I did mount them in the proper orientation. I'm still confused. I am going to move the wings for awhile. I think I am going to go with a off the shelf nylon motor mount (Sig) instead of the wooded engine rails anyway.