1. A Southern flag ought to be a flag that represents all residents of the South--old-timers and newcomers, people of every ethnicity, speakers of all languages (but learners of "y'all"). The South has moved on past the past that divided us. Its current identity maintains its distinctiveness even as it welcomes newcomers to participate in it and to belong. The new flag is for everyone who thinks of himself or herself as a Southerner.
2. It ought to be a flag that includes all of the Southern states, not just the ones that seceded in the Civil War--or were counted as "slave" states in sympathy with the secessionists' cause (e.g. Kentucky, which is included in the new flag, and Missouri, which is not). Thus, the new flag includes the traditionally-regarded Southern states of Delaware and Maryland; welcomes West Virginia back into the fold; and includes Oklahoma, where so many native Americans from the old South were relocated.
3. It ought to be a flag whose design confirms and strengthens the understanding that the South is part of the United States of America. The new flag design refer to the Stars and Stripes in a clearly symbolic way.
Here's my idea:
No, it's not upside down: "pole side" is the side with unbroken stripes.
The six stripes are for the six Southern states that ratified the original U.S. constitution and should be read top to bottom in order of ratification: Delaware, Georgia, Maryland, South Carolina, Virginia, North Carolina.
The triangular canton is in the lower right because that's like the south/southeast corner of the actual cartographical U.S., get it?
(A rectangular canton in that location would really look like an upside-down Old Glory from some 16-state time past).
The 16 stars represent the actual, real Southern states of (alphabetically) Alabama, Arkansas, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia.
While there are some similarities with the flag of Puerto Rico (which has five stripes and a pole side triangular canton with one star), they are coincidental. I didn't discover them until I'd already had the concept of six stripes and a 16-star triangular canton in the "cartographical south" of the flag. Furthermore, this flag furled or unfurled would have a distinct identity.
(Since writing this I've discovered another proposal for a new flag of the South. It has 15 stars and five stripes--no Delaware--and a design that to me suggests the Confederate "Stars and Bars." I believe that the times require a design that is a more radical break from the past.)