You don't have to get used to it, if you are comfortable in your regular posture. What posture do you use for your mountain bike (if any).
The faster you go, the more you are fighting the wind. Go twice as fast, and wind resistance increases by a factor of 4. I find I enjoy riding while toring, at about 75% the pace I would have if I were just going out for an hour or two. That level of output feels effortless. At that reduced level, I have almost half the wind resistance that I would have at 100%.
So the thing you have to figure out is whether your more aero position is worth the strain given you are going to have half the air resistance anyway. If the aero position is actually comfortable for 10 yours a day, day after day, then you don't need to worry. But if it strains you body in ways that will become apparent over a longer tour, then maybe you should enbrace the touring posture.