I've got a 2017 270 S and when lightly loaded it's right at 12' 2". When fully loaded with gas, water and gear it's about an inch lower. The radio antenna is slightly higher than the AC units, but because it's so flexible I don't worry about it too much. Just something to consider when designing the clearance height for repetitive usage.
Also remember to plan ahead, in that your next motorhome could be even bigger. I knew a guy who built a storage barn, with a little extra space, for his rig but a few years later traded up and the new "whale" wouldn't fit.
Good luck on you new shop, wish I could do that!