IMO.. Go the strap like what Surftech do.

DJ

3rd that, I have a Angulo Shaka AST with the insert handle and it weighs more than 15 kgs...........and its a pain in the.....................fingers!!!!

The long strap in the center is the best way to go IMO.. Most of the newer Barks and the new Jamie Mitchell boards use it.

Like this.. http://www.joebarkpaddleboards.com/boards/view/16/STANDUP+COMPETITOR

That lift up handle like shown above is also very good but you need to make sure it's in the perfect spot so it's balanced.. and I'm not sure how easy they are to buy.

The long strap lets you move your hand an inch or two each way till it's balanced perfectly.

DJ

My build here:
www.seabreeze.com.au/forums/Stand-Up-Paddle/Review/Kaholo-14-build/?SearchTerms=Kaholo

Keep it simple! Perhaps some wood under your deck that you can use self tapping screws for a longer centre strap or for a handle on the edge of the deck.
I used a flush mounted grip from Shapers on the Gold Coast and after deck was added, routed into the block of cedar I had secured to the deck underside and then dropped in the handgrip, sealing all with epoxy. You can roughly find the centre of gravity before the deck is added remembering the fin and fin box weight, which most companies seem to forget!
Contact me if I can help.

Once the center of weight is found, including the fins weight as JT mentioned and the liftsup fitted accordingly, it's hard to go past if you have to carry your board long distances as your fingers don't get clamped between the board and the strap, or if you have to climb stairs or steep walking tracks, as the liftsup is a ridged handle, with a slight twitch of the wrist you can lift or drop the nose of the board to clear the stairs as you climb for example without having to lift it higher.
I have only had mine fitted for 1 week had it out 3 times and would not be without one.
The strap handles are not flush mounted unless you use JT's method of routing into the timber which is a "why didn't i think of that" moment for me and may be the best for your situation, but i have seen damage done to a board when it was strapped on the roof racks on top of a board that had this strap, not nice for the owner, it was a surf sup not one of the bigger boards that you may not stack on top of each other anyway.
Hope the project goes well, good on you for having a crack, would love to see some shots of the final result.

Pete.