I am 6' and have quite a bit of room over my head. One thing you might consider is having them locate the surface mounted ceiling light fixtures in an area on the ceiling that would least impact your head clearance. You can see the standard placement in the following photo.
For what its worth, we have the Voyager fixed top on our EB SMB. We have the EB50 floor plan. We absolutely love the light and ventilation that we get from the upper windows and the open feeling the higher ceiling provides. We really like having the ability to stand and walk around while moving and as soon as we stop, if even for a couple of minutes. We have found that we leave the upper windows (in the top itself) in the open position almost all of the time. The interior is always full of fresh air and additional light due to these windows. The only time they are closed is when it is really cold outside or during rain.
All the best as you put your dream into reality.