Finally attempting a trench coat, talk me out of it or send me your tips

I'm finally going to attempt a trench coat. It's been on my someday list for years and I keep chickening out because it's a beast of a project. I'm thinking either the McCall's M8323 or the Vogue 1825 but open to other options if people have favorites. The classic khaki gabardine is what I have in mind but I'm tempted to do it in a cream or stone color so it's a little less Burberry-cosplay. Cotton gabardine seems like the obvious fabric choice but the good stuff is hard to source. Everything I find online is either too thin to hold the shape or has way too much synthetic in it. Wool gabardine for fall maybe? Has anyone tackled a trench before? The storm flap, the gun flap, the belt loops, the buttoned epaulets, the storm shield at the back, it's basically every tailoring technique in one project. I want to do it right with bound buttonholes and proper interfacing throughout. Also if anyone is sitting on cotton or wool gabardine in neutrals please please please. Trying to avoid paying full retail for something I'll mess up at least once on the muslin.