I know this sounds crazy, but if your lumber will fit in the wife's oven...set it for 225 degrees and "kiln dry" it for about 4 to six hours.
I make some outdoor signs and I remove half of the thickness over 80% of the surface area and I only get about a 1/16" bow over 12"
BUT...I use big box 2x6s split them down the middle and cut to 26". Kiln dry them overnight and make a glued up panel out of the 2-1/2" pieces.
I've been looking for a cheap used pizza oven! Trying to save my marriage!