If you wear light blue socks, might want to try to match that pocket square with them, rather than just making it the color of the shirt. Sounds like a nice getup though!
If you have one shirt you like already, you can use that for measurements. Otherwise, but one MTM shirt from a local clothier with a good rep (it'll cost you but it's worth it) and use that for ordering from online suppliers. You can't...
OP - you could also buy a MTM from a brick and mortar local guy (probably run you around $150) then use that to send to companies like Blank Label. They'll copy it to get your measurements and send it back for free. I can't compare...
Awesome detailed review! I've been looking for comparisons between these guys, Blank Label, Indochino, Proper Cloth and a handful of others. Actually thinking about doing a "battle of the MTMs" post on my blog. Could be kinda...