Uncontrolled airport departure-again...

I know this question has probably been answered thousand times before
on this forum. I am based at s50 in washington with no instrument
approach or departure procedure. It is class G to 1200 and then class
e plus some class b around.

How can I depart IFR from this airport? Do i need to depart VFR and
stay below 1200 and pick up my clearance or can I get a void time
clearance, be responsible for my own obstacle clearance and separation
and depart essentially at 0/0 (if i ever thought that was a good
idea?) The minimum vectoring altitude is 2000 feet. Just thinking
about those days where the ceiling is 800-1200 or a 400 feet fog layer
where it would be nice to get out.