[villagetinker]

Lots of good points and suggestions, IMHO, I would suggest this:
1. Lower the speed limits, and work with the police for enforcement of the new lower speed limit. At a minimum, radar speed signs 24/7 for several weeks or more.
2. Actively engage the Sumter County officials to point out the differences between this section of Morse Blvd, versus several of the other similar roads, so they understand the local residents concerns.
3. Perhaps install additional signage (the developer??) indicating this is potentially a hazardous area, and to SLOW DOWN.
4. Get a suitable group of people together that well represents the affected villagers, and work with the developer and the county for a permanent solution.
I think you have an excellent start here with various options and opinions, all of which seem to be very supportive of a fix being required.