Upgrading a FAO Fishing Boat - First build

Yesterday I saw photos of the FAO fishing boats for the first time. As I have always wanted to build this boat first, (6.3 meters), I have decided to get to it.
I do appreciate the auxiliary sail, and would like to emphasize this ability. Now a couple of questions:
1) If I remove the rear rocker to increase the speed/planing, will it reduce its "sea worthiness"? Should I leave the design alone? I plan to do a lot of fishing from it. I already have a down rigger and a fish finder that I want to use.
2) I would like to add extra frames to stiffen up the boat, and put an antique 18 hp Johnson on it (could turn into a 15 hp 4 stroke at some point). Does this sound sensible?
3) Would the design benefit from small bilge keels to assist the sailing, or is it better to leave as is? I will likely make a simple sale rig for it, and plan to use the sails for pleasure and to cut down fuel costs.

Thanks everyone for your input.

 

For low power have a look at

http://www.dhylanboats.com/pointcomfort18_plans.html

 

The fao skiff has been. Reengineered by

http://www.bateau.com/studyplans/PG22.PDF

18hp is too small.

20,22 and 25 footers drawn. A 20 footer will need 30 hp

 

Low power sail assisted skiff

http://www.peterschermer.nl/

http://www.kitetender.nl/

 

Chesapeake Skiff with Sail Assist

This is an interesting looking plan. It just looks classy, and I think would make a comfortable ride.
I don't think I should tackle a kite assist until I have learned to sail with a simple, ordinary sail. With the kite, do you go where you want to go, or where the kite decides to take you?