There is a lot of solo content in EF. The whole canyon, most of the The whole perimiter of the Monitor/Minotaur area is solo or non-aggro Ice Maidens, In the tunnel leading the other direction the Ice Frights are all solo aside from the random Nightmares spawn, the ice golems are all easily avoidable. Spiders aren't heroic I don't think, you can easily move through the Numbfoot area and avoid aggro from Heroics if you just keep your eyes open. Aside from Terrors most of the huge basin with Tundra Jack is solo. The Ice Giant cave is all solo.
Make a solo questline involving existing creatures, please. Don't change what exists to create it though. Norrath should not be a place you can run around with a no sense of danger.