1. If you have a dado shims, do you have a dado set? Is it flat grind?
It's pretty common to just use the other blades for this operation.
Some people (most) like to use the blades on the wrong side so the
fibre breaker is inside, next to the tenon rather than on the outside
as designed.

2. They have been brining in CMT blades at the shop I'm working in and
sometimes they seem work better than the Forrests. Especially the thin
kerf ripper that is marked as "Excellent" for ripping. It is.

3. Use Thrust Washers: I will be doing some research with my machinest
guy soon for a similar spacer setup for quick accurate gang ripping on
my 18" Woodmaster planer molder (still in the crate but not for long).
Currently I am thinking I can use what they call Thrust Washers. I can
get them in the right ID's and they come in 1/16, 3/32, 1/8 and 1/4.
All with a +/-0.005 tolerance in width. Even with stackup that's
acceptable for me. Its 1/200th of an inch each. I think it will be a
problem for wider widths so I'm looking into having some tubes cut and
percision ground, if I can't locate any off the shelf parts.