Help with Boat Build

I have a Dagger Reflection 16 vintage 95 in royalex that I am rebuilding. It came to me with the gunwales already rotted out and torn off though, so I do not know the correct placement of the seats to get close to the original configuration.

Can anyone that has one (or has the specs) advise of the measurement to the seat fronts for all three seats (there is a center for solo).

Also there is a chalky residue on the royalex, and though I’m not particularly picky about form over function, since I’m spending the time to rebuild it I wouldn’t mind spending a bit of elbow grease to clean the outside. Any suggestions that are locally available from Lowe’s or such. I don’t have easy access to any boat stores for fancy preparations!

Thanks in advance for any help