I want to install a cutter-stay and two back stays on my 50ft alu
sloop, 1) to add a cutter-jib to my sailing options and 2) to stop the
annoying pumping-motion of my mast.

So my options a

1) Running backstays, which are relatively hard to install reason why
I would prefer:

2) Fixed backstays, to be installed on the existing puttings of the
lower stays and the other end on the exsisting mount of the
intermediates. When fixed like that, there will "room voor the boom"
on downwind courses.

Problem is the very small angle the fixed backstays will make compared
to the mast. They will be fixed to puttings one meter before the mast.
The other end will be mounted 14 meter high in the mast.

What do you think about the forces such an installation will cause
when using a cutter stay in heavy weather?

Regards, Len.