George, Please to not take offense. We both agree all Southern States should formally recognize Confederate History Month and pay respects. My response to the question would be to answer for Senator Price since he choked up and booted it.
I would consider writing a letter that does not mention race at all and mentions slavery very little and very concisely. The primary reason for Secession was the citizens of the Southern States were tired of being over taxed and receiving little proportion in the way of federal funds for infrastructure. Without slavery (which was legal), the South would not have been so prosperous and therefore, not subject to so much looting by Congress and the Executive Branch. Southerners believed State sovereignty was guaranteed by the Constitution.
The primary reason for the unnecessary war was that the Lincoln administration wanted to "preserve the Union" (conquer the CSA), centralize the U.S. government and make the States subservient. So, they were successful.
There was an alternative to Secession and to war that would have made everyone but the Republicans happy. And if I wrote a letter and mentioned slavery more than once, then I would say that slavery was dying a natural death like it did in Europe and all of the slaves could have been purchased by the federal government for a lot less money than it took to wage the "War Between the States".
Neither your letter or the one I outlined is ever going to get the point across to willfully ignorant people, but there are probably some intelligent folks who will listen if we generate more light and less heat. The haters want us to talk about race because that is their tactic and they are good at it.