Like you a dont think the vikings and the MP go together, your point about the age of the works on OI is good though as i suspect the common theory is that they are about 50/80 years older than the DDM discovery date of 1795, i think they may be a little older than that, but not by much.
for what its worth i think the vikings did make it as far as NS, they were tough, adventurous, resorceful and willing! thay make for great candidates for extensive travels in that part of the world.
Quick pass me a spade! I`ve had another idea.