Biog Living Spaceship - covering up.

I was having a problem adding Magic Sculp detail over the original clay at the front of my Biog Living Spaceship, in that the original clay is SO crappy and cheap, it would crumble and crack with the least amount of handling.
So, to get 'round it, i've added Magic Scup all over the ship to seal it in and keep it safe.
Now i can go back to detailing.
Got a bit of a worry though - this solid airdrying clay core followed by the amount of Magic Sculp is making this beastie HEAVY.