Following different scrips
ftnoob, in my opinion, your solution looks fair and good (generous).
But first, yes, I am.
Second, why do you say you think returning the .5 RR wouldn't even be considered? I think it passes equity, KISS and computer tests.
Third - and minor - I'm not sure how your suggestion does vis a vis KISS. It seems more involved. This would seem to be ever more important (e.g., the bind's in the cheese if the issue were to be addressed at all this year) as time is short before the new regime. It's short for making a change, for Customers understanding any solution, and for working through the process. (But I see the attrition advantage to Southwest that accompanies any coupon offer.) Also, it would appear to be even more accessible and appealing to the revenue passengers also standing at the counter, than returning the .5 RR - a different scrip - to the RR Customer.
Fourth, that said, I'd take your/Southwest's offer.