I’ve made a few doors including ones like your picture. Loose tenons are superior to dowels, I’ve seen plenty of joint failures in windows and doors with dowels. Also, if you haven’t considered it, make the bottom rail wider than the rest of the door. Visually the bottom rail looks too thin if it the same width as the stiles and upper rail. I usually go 1.5-2x the width.

I’m embarking on a set of doors for my parents that might interest you. I have a bunch of Douglas fir that is not quite 1-3/4” thick. Also the grain is not that tight visually, but otherwise it’s sound. My idea is to mill the fir to 1-1/4” and faced with some 1/4” vg Doug fir on either side to get to 1-3/4”. Furthermore, the core will be constructed with the horizontal pieces capturing the vertical pieces. The faces will be arranged more conventionally, so in essence I have a bridle joint without having to do any joinery.

In your case the outer faces will be the two different woods you desire. Expansion rates of dissimilar woods might have to be accounted for but for rails and stiles it shouldn’t be too great.