Just a couple of ideas off the top of my head. Sorry if these have already occurred to you and been discarded
As has been said up and over doors would be awful, but as you say, the customers is always right, even when they're wrong. Excellent workmanship a very impressive traditional build.
I've just finished building an oak porch using 5" x 5" posts and 6 x 4 sole plates. Really pleased with the end result (see pic further below). Of course the swaying wasn't an issue with the secondary posts at the front. Half lap joints with the posts tenoned through a mortise that's through the half lap. The whole thing doweled afterwards and it all locked together. Glazing to follow next month.
Good luck on the build you're doing. I am very impressed with your work I have to say.