Hakan,
No, I didn't have any concerns and I think the large majority of builders don't have the skin on at this point because of all the wiring and mounting of the various instrument modules that must be done after hanging the engine. Although I think some may have had more of their panel done prior to hanging the engine than i did but mine is currently being built by Stein and won't arrive for a few weeks yet. Either way I wouldn't worry about having the top skin on as all of your critical structures are set in place by this time.
Bruce