It’s pretty unbelievable to me that a product like this that’s ‘made’ for the 200 requires so much...customization.
Mine did not require any modification or stacking of spacers to mount and it shouldn't.
Are all of your spacers the same size?
It's been a lot time since I did mine, I don't remember anything special to the install. I put it together on the garage floor, set the spacers on the roof to compensate for the curve in the roof, test fit, RTV and then bolted it down. There might have been a little gap but that was fixed when the whole thing was torqued down.