First, no, there is no reason against it, other then having the balls to fly 200nm over water.
Tinkwall is really a nice place to go! The major concern I have is weather. At Tinkwall the stationed island hoppers call clear sky everything with clouds above 500ft - if they are able to see the nearby windmills, it is good to fly ... Fog and mist is almost always an issue there, so it would help, if you had at least some basic knowledge on IFR. When I was going there, I had NVFR and was current on CFVR, which helped keeping calmer. I was not confident to take the C172 Norway - Shetlands and decided to do the big detour France - UK - Scotland.
For trip planning that way I would advice to get the point of no return under current wind as a waypoint. It may happen that all alternates are foggy and unreachable, so you have to be sure at least one airfield is perfectly clear upon arrival. Also, be trained in crosswind landings - it happened to me twice that one runway at Sumburgh was closed. Otherwise your alternate is fly back. If you have 25 knots head the point is closer then you think.
Last edited by ChickenHouse; 4th Aug 2014 at 08:49.