if you just want to try it blocked to see if you prefer it then you could do what i did, two plastic wine bottle corks and tube of silicone sealer for the front, and a piece of wood, a wood screw and a rubber backing disc off a black and decker sanding attachment and sealer for the back, will block all the holes up nicely.
TBH though you may as well get some nice expanding rubber bungs for the front and a piece of stainless with a drain plug for the rear and do it properly, because once you block it up i dont think you will ever want to unblock it.
i dont think you will get an SR5 dry though, theres always an inch of water in the bottom, though on saturday in NOS4r2's boat it was more like knee deep some of the time
I did notice some water coming in NOS' boat up the leg at some speeds, but only a very little so i guess all seariders may do it to a certain extent, i have seen it on mine too at around 20-25 knots when trimmed right in with 100 liters of fuel on the stern. not noticed it at higher speeds, trimmed out, or with less fuel. Raising the engine one hole helped a bit. its one hole off the lowest now.