The Canadian Air Cadet manual for winch and auto launch of 2-33's specifies the weak link should be 2 x max gross weight and this gives 2080 lbs.

We recently winch launched a 2-33 at a neighbouring club and used a 1925 lb rope for the weak link.

For a 1-26, I would use the same (2x) rule of thumb.

With the weak link at this level, you can not put more than 2g on the airframe.