The law in this country doesn't care what churches validate as "marriage." Never has, never will. If you want to go the St. Looney up the Cream Bun and Jam church and have them solemnize your marriage to your Aunt George, his pet squirrel and the Astrodome, the law won't give one whit, as long as you don't appear to be a threat to yourself or others.
This means to me that things are well in place for adopting NosyNed's proposal.