Dan,
It will take a long time if you use 400 to remove the finish.

Is the subject a built up structure with silkspan or some other covering or is the subject all sheet?

If you sand the finish off you will probably cut into or through the covering causing additional work.

A technique that I have used is to get a roll of paper towels, a can of acetone, rubber gloves and (outdoors) wet the towels with acetone and wipe the dope off, changing towels as needed.

Don't soak the structure with acetone (may weaken glue joints) but keep the towel wet enough that the dope is softened enough to allow wiping off.

Messy and takes a while but, if careful, the covering can be saved with out damage to the structure. If you want to remove the covering, apply enough acetone to the covered area to soften the dope and allow the edge of the covering to be lifted.  I have removed wing covering one panel at a time using this method.

Hope this helps.

Dan,
It will take a long time if you use 400 to remove the finish.

Is the subject a built up structure with silkspan or some other covering or is the subject all sheet?

If you sand the finish off you will probably cut into or through the covering causing additional work.

A technique that I have used is to get a roll of paper towels, a can of acetone, rubber gloves and (outdoors) wet the towels with acetone and wipe the dope off, changing towels as needed.

Don't soak the structure with acetone (may weaken glue joints) but keep the towel wet enough that the dope is softened enough to allow wiping off.

Messy and takes a while but, if careful, the covering can be saved with out damage to the structure. If you want to remove the covering, apply enough acetone to the covered area to soften the dope and alloy the edge of the covering to be lifted.  I have removed wing covering one panel at a time using this method.

Hope this helps.

Ditto what Jim states, but I've used cheap lacquer thinners to effect the same result. 

Ditto what Jim states, but I've used cheap lacquer thinners to effect the same result. 

finally ,, someone who konws what to use cheap lacquer thinner for!! ( NOT IN THE PAINT)

Thanks guys!
I never would have thought of that. I just have to strip a profile fuselage, so that will be easier than sanding...
Regards,
Dan

Lots of ventilation, NO fans unless they are blowing into the space,,
hand protection, good nitrile goves,,
Its really easy to get painfully high from strait thinner used that way, it evaporates fast! and that puts a lot of fumes in the air, and you wont notice it as easy as you would think, especially with a  respirator. I have stripped cars with straight thinner, ( yeah stuff goes wrong,, ) sometimes when you paint you blow it so you wash the fender or whatever down,,
anyway, just be overly cautious doing this,,

Since this is a sport plane w/profile fuselage do yourself a favor and just consider the previously applied dope a filler coat/primer, cover it w/a coat of light grey (polar grey and white combined) then spray your color and clear. The amount of weight you save completely stripping the fuselage isn't worth the effort and smelly mess that bathing it in stripper or lacquer thinner will make...just MHO.