you will need to flip the hull over.
make a rack out of 2x4 .120 or 12 gauge tube..
make it like a dolly trailer so it will pick up the stringers.
get a drywall straight edge..they are cheep. less than 20 bucks.. it is long ,use it to check the hook.
set it on edge.
if there is alot of hook and you will have to use the green stuff to fill it in...
easiest way is get a hutchins air file.
then a 2 in wide x1/4 inch thick piece of aluminum..how ever long you can find.
drill it and bolt it to the air file with the 10/32 screws.
use psa long board paper.
if you are only leveling the current gel.. 150 grit will work.
if you are filling it with green stuff... then 40 grit..
run the file slow... let the paper slowly do the cutting.. like a fat beaver nibbling on your wood.
evercoat makes some green stuff... use that . DO NOT USE BONDO OR KITTY HAIR to fill the bottom.
bondo will hydraulic off and the kitty hair is a bastard to level.
bondo is ok for very thin fillling...under 1/16 in.. remember it is for cosmetic purposes... not structural.
it doesn't flex enough. imho.some might have had good results......bondo must be coated /sealed if used... it is hydroscopic....
stay off the strakes untill you get the bottom straight..
then go back and do the strakes... or you could loose the shape.
there are ten ways to skin a cat...

this is how i did it.