I'm busy designing a new character and I'm thinking about a character with only marksman as weapon skil.. (combined with conjuration as only other offensive skill)
Together with a very high starting Speed, Light Armor and some sneak+illusion skills... would it be a someone who can survive though battles?

EDIT: mayby handy to mention I use mods like BTB game improvemets, Marksman enhanced and Thief expierence overhaul...

Sure, why not? Marksman and conjuration is a classic "arcane archer" build.