take a look at the calculator at
shorten your top beam and compare it with the stock version.
we already have problems in the bottom corners where the tension is the lowest,
narrow your workpiece until the minimum force is about the same and you will see
about where you are.
then compare it with a 12’ top beam, which is a common upgrade and that will
show you your best area
I would guess that going from a 10’ top beam to a 9’ top beam will make your
equivalent work area be 7’ wide, and compared to a 12’ top beam, somewhere
between 5-6’ wide
now, these numbers are assuming you still try for 4’ tall work area, since the
problem is in the bottom coreners, going to something not as tall will also