I did, on Eurobike, on the cruiser variety. Not Coker I think, but the Taiwan catalogue one. Felt way heavy, but once rolling...OMG, out of my way! The cruiser was hard to make a u-turn with on a regulation bikeshow aisle, but the MTB version could be tweaked quite a bit to sort that. Still, don't start a project like this before you've already dedicated a fitting part of your garage for it!
My 28" townie weighs more than "my" 36"er would, and handles just fine with a 68º or so head angle. I have good faith a 36" MTB done properly (lucky guesswork?) will totally stun the world. Sand traps will be a joke, traction unlimited. And what about the truly steep stuff, 2 wheels stuck to the ground!