What's the latest on "forecast icing = known icing"

I thought I'd try to make the discussion of flying into known ice more
concrete with a scenario. The following actually happened recently.
(Not to me of course ;-)

The leading edge of a cold front has moved in. Airmet for light to
occasional moderate rime and mixed ice in clouds and precip. Forecast
freezing level 8000 and above. Pirep of light ice at 8000. I've filed
for 6000. Field is at sea level. MOCA is 5000 due to a mountain range
that the airway crosses. My heading takes me through the leading edge
of the front and into VFR conditions beyond.

Can I legally launch?

Suppose I do launch. I enter the clouds at 3000. At 5500 climbing I
start picking up light ice. What should I do? Options include:

1. Do nothing. This is not an entirely unreasonable option in this
case becase a) the ice is light and b) I can reasonably expect to pop
out of the clouds in 10-15 minutes.

2. Climb. This takes me further into the forecast freezing conditions,
but buys me terrain clearance in case things get really dicey.

3. Descend. Seems like a bad plan because it may or may not get me out
of the ice by the time I hit the MOCA.

4. Go back. Also an unattractive option because I'm all but assured of
remaining in icing conditions while I maneuver to get set up for the
approach.

5. Declare an emergency and descend below the MOCA.

6. ???

rg