FSD/Autopilot minimum speed or "fixed" speed

I often like to set the max speed in FSD to the speed limit for highway driving for the sake of efficiency. However, I'll encounter construction zones where the speed limit drops to 55 mph, and the system will sometimes jump back and forth between 55 and 65, thinking the construction zone has ended prematurely, then decelerating yet again at the next 55 sign. VERY irritating.
There should be minimum or a "constant cruise" setting, that will allow a more or less fixed speed, regardless of construction zones, etc. that will only slow down in accordance with changes in the flow of traffic, and (obviously) for safety reasons. At least in CA, when there's a 55 mph zone, people MIGHT slow down from 80 to 75 or 70... MAYBE 65, but I'm sorry... pretty much NOBODY is slowing to 55, and doing so could actually be dangerous in itself.
This would represent a huge improvement to FSD/Autopilot.