Worth a try but:
I think that 30 Sq Ft will not make up for 120 lbs more on those boats as they are not the floatiest.
You cannot not really get a portsmouth number as there is not one for that configuration. I am sure that your "friends" will let you play though.
If I were thinking about coming out boat for boat on a Prindle 16 and wanted to blow them away, I would find a big Performance Catamarans boat that uses the same mast step and put the whole rig on it. Image a Nacra 6.0 rig on a 16? Wow!
Might as well add the skrecher. What the hay?
Good luck on the experiment,
Dan