OK, everyone agrees the run flats are pieces of sh*t, but I am going to have to live with them until they wear out.

I note in the manual that BMW recommends different tire pressures for different driving speeds and passenger/cargo loads.

What pressure is best for handling, preventing the tires from developing the dreaded road noise, reducing the uneven tire wear due to performance cambering, and reducing the possibility of damage to the rims.

I don't plan to drive in excess of 100 or even 80 and in most cases will be the sole occupant but I assume the higher pressures that those situations call for would be best even for a light load at commuting speeds, although the ride will be rougher. Am I right?

No. The pressures listed on the door jamb are almost ALWAYS the best for ride and tire wear. Inflate them to the proper amount as per the door jamb and the load you carry. Since you are saying you do not carry loads, I would go with the lowest psi listed on the door jamb for front and rear (likely listed as "up to 4 or 5 passengers"). If you inflate them to max load psi, they will wear down the center prematurely and your ride will suffer.