You stated that the model flies well so the negative incidence is probably part of the design. I have a .90 powered Edge 540 that has noticeable negative wing incidence (you can see it just by looking at the wing slots). It would not take off unless it hit a bump on the runway. I bent the tail wheel strut to the lowest possible position and it’s OK now but disappointingly, it will never do a realistic wheel take off. The tail just won’t fly on roll out; it needs to be stuck to the ground to give the wing sufficient angle of attack. Similarly, all landings are 3-point. I’ve seen some other tail draggers at the field whose owners installed larger tail wheels or kept the struts long in an effort to improve ground handling on a grass field. Sometimes this is a mistake. Similar problems can develop on tricycle gear models when the nose wheel is too short, pointing the nose down, but these planes can still rotate into a good angle of attack because the tail has room to drop down to the surface- but a tail dragger cannot rotate any further than the tail wheel position allows.