I wouldn't mind adding a few anchor points in the cockpit for use with a safety harness. I was thinking fixing them to the front of the cockpit lockers to get them off the floor. I wouldn't imagine there would be a great deal of strength in the FG there without a substantial backing plate.
What do you think would be an acceptable size plate?
Cheers
Edit: There is already one for the helmsman. Would having additional in the cockpit be overkill? If there where two of you in the cockpit in conditions where you deemed a safety harness in the cockpit necessary, could you share the one anchor point???
Always nice if different tie-in points are placed so you can reach different parts of the deck from each.
Sometimes cockpit locker sides are relatively thin - if they're only 4mm thick and flat, then I wouldn't like to tie on to less than roughly 200 x 200mm backing, but as you know going bigger is never a bad thing provided you don't go overboard.
I now have 4 in my cockpit, 1 for the skipper, 2 each side on the inside of the coaming and one next to the companionway entrance. When we use the harness, the rule on my boat is to clip on and off as you come through the hatch.
I have just used oversize S/S washers as backing. The fiberglass on mine is very thick in the cockpit.
As a supervisor once said to me during my apprenticeship, when I asked him if he thought something was strong enough. "If you'd be happy to hang off the Harbour Bridge by it, then it's strong enough, because it'll be your life that's at stake." 
Cheers allSelect to expand quoteGravy7 said..
But as Karsten says "don't go overboard" 
I suppose that was where I was getting at. At some point it must become overkill
I wouldn't put any additional anchor points in.
Every hole is a potential leak.
Where are you planning on sailing and is it racing or cruising.
If cruising, minimum on deck and if the the jack lines are running past the cockpit hook on to them.
We have 4 in the cockpit, 2 aft of the mainsheet traveller and 2 just aft of cabin coaming, within reach so you can clip on as you leave cabin, .... we have to have them within reach to comply with Cat3 for racing.
We have used Wichard and they say oversize washers ... guess at the end of the day, it depends on what you think your life is worth
We put 4 pad eyes in the cockpit to satisfy CAT 4 safety which says you have to be able to clip on exiting the companionway. All are on the vertical of the cockpit lockers which are reasonably thick and was also the easiest spot to mount them. Currently got big SS washers as backing plates as the ones to match the pad eyes were out of stock (the washers are probably bigger than the matching backing plates anyway), bit of butyl makes water leaks non issue. I wouldn't want them on the cockpit floor for trips and also any leaks would be straight down into the cabins.
I prefer to be clipped on to the Jacklines though, as it enables easier fore/aft movement from helm to cabin top winches and protection under the dodger (where you spend most time in bad weather). We run our Jacklines between the fore and aft docking cleats. That might not be as easy with your twin wheels and bigger cockpit. I have seen a setup with jacklines along the cockpit floor which makes movement about the cockpit very easy but also looks like it could create a trip hazard.
