I am probably not the best person to advise you as I haven't built one of these machines but in general the ideas apply and size doesn't affect things much.
I don't follow your issue with the tail, without seeing exactly what you have it is hard to know what is going on.
If you have things correct and no tail stops you should have this. The pivot should be something like half way round from straight back at say 45 to 60 deg and inclined at about 20 deg and pointing downwards at the 45 or so deg direction.
If you had no tail stops the tail should hang down at the 45 deg angle at 20 deg below horizontal. You arrange a stop so that the thing stays something like straight back, at this point it should be about horizontal and will be held by gravity against the stop. When you bring it to the furl position it should rise above horizontal nearly 20 deg. The 20 deg point would actually be in front of the blades and directly opposite the low point with no stops. You need to stop it parallel to the blades to prevent it striking and that is your other stop.
In real life the thing pointing straight back will not point the blades directly into the wind as you will have an offset thrust from the alternator offset. You need to set the back stop some degrees past straight back towards the direction where it would hang with no stop. It really needs a lot to keep it directly into the wind but I would compromise at about 30 deg, any more looks silly and starts to mess up the control force curve. If you end up with the blades running at 30 deg to the wind in normal operation that will have very little effect.
I would arrange the tail to be about horizontal when offset away from furl at about 30 deg and sitting on the stop. If it droops a little at this point it won't matter but I wouldn't have it rising.
Many people have extreme difficulty visualising all this and I am not sure whether you can imagine what would happen without the stops, it's a bit drastic to remove them but much easier to understand the whole process.
Your 12.something inch offset should be safe. If everything is set up at the correct angles then you have a tail moment that is too large compared with the moment from thrust on the alternator offset. You can reduce the hinge vertical inclination angle or make the tail lighter. I strongly suspect the 20 deg is rather large unless you make a real effort to keep the tail light.
The less you make the hinge angle the more critical it becomes to the tower being vertical but otherwise you can reduce it if you can't lighten the tail.
I somehow suspect you may have the geometry wrong somewhere but without seeing it I really can't comment. I hope you can follow my description but it is not easy to describe.
Flux
