Thank you for the tip Wo3Dan,
I'll keep those tips in mind for the next time.
As my file kept crashing by using the drape tool, I handed it over to a colleaugue who did it in 1 minute using Rhino.
The trouble with the sketchup drape tool is that it is basically a ruby, and thus has difficulties with large amounts of geometry....and in a lot of cases, DWG site imports are full of it.
Friday was really a day of Sketchup frustration.
Anyone sells a SU stress ball?