Any way to get more caster adjustment without newer adjustable CA?

If you can shorten the effective length of the lower strut rod without causing the lower control arm to bind throughout its full range of motion, you will gain significant positive caster. This can be done by cutting the rubber bushing a bit or machining the forward shoulder on the rod a bit further back.

Adjustable strut rods make this an easy update. Be sure to keep an eye on the general position of the front wheel in relation to the fender openings (front to rear) when performing this mod.

This is true, but the most important part is to ensure there's no binding of the LCA throughout it's range of motion. Don't sacrifice the free movement of the LCA to get positive caster, keeping the LCA moving freely is the first job of the strut rod.

I use adjustable strut rods on my cars to fine tune things, and I've found that I can usually get some additional positive caster by shortening the strut rod length compared to stock without causing any binding within the range of motion of the LCA. That's with adjustable strut rods and poly LCA bushings. Cutting the strut rod bushing down and using factory strut rods would shorten the effective length, but if you shorten it too much and get binding you need new bushings. It would be a lot more trial and error than using an adjustable strut rod. The range of factory tolerances on these cars is such that what works for a strut rod length on one car might not necessarily work without binding on another.