Couple of things immediately spring to mind...
If that Florida based C182 is "N" registered then you are a PPL - not a CPL/IR (if you understand my drift).
Consider doing the "Instrument Foreign Pilot" written exam in order to become, effectively, an FAA PPL/IR.
Second - and biggest - hurdle is that, for every journey I've heard about EASTBOUND (USA to UK), the Authorities will not allow you to leave Newfoundland towards Greenland unless you can show previous route experience.
I know others will argue this - but an ex-boss of mine used to do it fairly regularly - and was grilled, every time.
His first words of advice for anybody trying to do it was "take every day as it comes - you could be weathered in, in Greenland, for days and days - don't set yourself a time target - just take it as it comes. The "point of no return" comes fairly quickly in a light single - even with ferry tanks".