"Now I have a question about the secondary HSAB's and their function.
I would love to just swap out something external when the outside temps go up and down."

First, I would not expect the secondary HSABs to have any effect on the 50MPH cruise AFR since I can't imagine that the secondaries are operating on the main circuit at that point.

With respect to their function, my understanding is that the HSABs are tightly coupled with the boosters. The booster design will produce a particular "signal" for the main circuit. The booster signal by itself is non-linear though, with a non-proportional increase with air flow. The high speed air bleed acts as a "trim" for that signal. When the booster and air bleed are properly matched, then the AFR curve should be linear with air flow. If the air bleed is too small, then not enough booster signal is trimmed, and the result is more fuel flow, and as seen in my recent experiments, a AFR that gets richer with RPM. If the air bleed is too big, then the opposite happens, with a AFR that gets leaner with RPM. What I don't know is the exact sensitivity to the bleed size, and whether the secondaries operate in a narrow enough region to allow a measure of variation in bleed size around the ideal point. On a race motor that operates in a somewhat narrow region (say 5K-7K) the bleed might be an easy way to make an external adjustment. On a street motor, the situation may be different. Worse case, you will need to experiment. However, some sort of data logging would really be helpful with something like this.

All that said, I thought you were a proponent of using the float level to fine tune the AFR via external means. That sounds like a good idea to me, particularly on the secondaries. Are you concerned that does not give enough adjustability?