Ah. Europe would be relatively (key word there) easier because of the unified airspace and standards in place for the most part. Given the expected range for my design, it would not be hard to go trans-Atlantic (with the normal GA stops) and if I have the means and availability to do so, then I plan to do so. It's not like I'm going to be puttering around with non-certified avionics or anything short of a turboprop engine so I don't see any reason why I won't be able to do so.

Where it might be an issue is if I get a wild hare up my butt and decide to go beyond Europe to explore. That could be an administrative challenge.