Has anyone modified their splashwell for bigger waves? Such as closing off
the back with a bench style seat or having another piece of aluminum fabricated to keep the water out of the deck area. Pics or links would be great.

http://www.wavewackers.com/

Or... https://www.whitecapmfg.com/

Wes,
Go to a machine shop and have them fabricate a 6 inch aluminum channel to fit across the front of the splash pan. Have them weld flat ends on the channel of the appropriate size to bolt to the sides of the boat.
Place a rubber gasket on the lower side of the channel before installing and it will keep about 95% of the water that might accumulate in the splash pan out of the floor of the boat.

As long as you are doing this, you also want to check the integrity of the splash pan with respect to the transom. i.e. fill the splash pan with water from a garden hose and check under the splash pan to be sure that all areas of the splash pan are sealed with respect to the transom.

Over time, lots of boats develop leaks in the splash pan to transom area and if water enters the splash pan, it runs down the inside of the transom where it will need to be pumped out with the bilge pump.

REW

p.s.
The addition of the channel across the front of the splash pan also adds quite a bit of strength to the back of the boat.

I modified my splashwell to the tune of $150 or so and purchased some "WAVE WACKERS" which work very well.

I haven't looked recently, but in past years, there were several different manufacturers who made boat models that had a flip up board that normally lay flat on the back area of the boat. When needed for rough water, the board flipped up and made about a 10 inch wall at the front of the splash pan. It was a vinyl covered piece of 1/2 inch plywood, that had a full length piano hinge to mount it to the back area of the boat. Then, there were locking pins in the rear sides of the boat to hold the board vertically to deflect water that might come over the transom.

You can check other boat manufacturers, or look into some of the past models of these various other manufacturers.

REW

...on a Sea Nymph I ran during the 1980s. Most of the time I had no problems with the splash well, but on windy days with rough water it got miserable if you fished out the back of the boat. I had a local canvas shop install a snap-in vinyl coated canvas panel which I would put up when things got wet. This worked pretty well for me for many years, and cost all of about $15.( in 1980 dollars) installed. I note that my present Starcraft uses a similar snap in canvas panel to hide the battery from view.
Doug