John,
That was good! ...Perhaps doing also the nails and hair...)

My logic was what is called Forgetful Induction, according to a book I have... overlooking the obvious! (That data is an optimistic estimation for the best possible scenario for that objective- definitely not our case!!)

A team from UFSC-Brazil published their findings during tests with these engines (see www.aerodesign.usfc.br - in portuguese) at various speeds on a simple wind tunnel. They obtained 12k static, 12.2k at 40 mph wind speed, with the thrust varying linearly from 10.22 lbf static to 5.46 lbf at 40 mph... that's close to half what I expected in terms of thrust, isn't it?!
Still, it's enough to accelerate (no drag) 60 lb from zero to 30 mph within 200 ft in 9 seconds. Deduct drag and rolling friction and your 40 lbs GW estimate is pretty close...

Now the winglets: commercial airplanes' winglets are optimized for cruise (they do not need such a strong twist)... The one suggested above would be optimized for max Cl... and be toe'd in at the base the same angle as the wing aoa for max lift...
I can see clearer now the rain is gone...
Lots of learning! Thanks!

Souza.