This is why you have such pessimism directed at you. You said that you going to try and design an ultralight by using TLAR thicker aluminium to arbitrarily strengthen it instead of recalculating. If you do the calculations as most of your skeptics have done on their own projects, you might appreciate why they are responding the way that they are. If you don't do the math, the extra weight from the bits that you overdesign will further overstress the bits that you underdesign. You think that you need a stronger tail, but you don't know that, you're just guessing. In my own design, the flight loads exceed the tailwheel loads. I only need to attach the tailwheel solidly enough to take landing loads to the fuselage that is strong enough to take the flight loads and I'm good. On to the next part. Calculating the loads on the various parts is fairly easy. If you compare the loads of your project to the loads on part X of the donor project A, you can then make a judgement as to whether part X is too weak, about right, or too heavy. Perhaps part X on donor project B is about right. Perhaps you need to redesign it. That is where the real tedium starts Or do you want something that is overweight and understrength?