Re: Large waves
Great story; a lot of good take-away points:
For those of you who seldom use the bilge pump (single day boating) you need to verify it as part of your pre-launch proceedure. A good idea is to have two.
The bow-riders (like in your picture) that are popular on lakes aren't in open water for the reason you experienced: their design makes the bow a big scoop and they don't have the chines or spoon bow to throw water aside. You would never take that boat off-shore (including Gulf, large bays, etc.)
Now that you know you can get caught short, buy a bow cover--a strong one--and carry it with you; it turns your boat into a closed bow and that helps shed water. Also seal the bottom of your rub-rail, a great source of water in rough weather.
All your passengers should be wearing their PFD's, buckled tight, for the obvious and to prevent bruised ribs in the boat. INstruct your passngers that you are in a serious situation and you need their immediate compliance with your orders. Cell phones go in a zip lock and in your most secure pocket and at least one of you should have a flashlight also secured and water tight on your person. (you do have zip-locks for this on board, right?)
The guy who jumped up and went over the stern? leave him. No but seriously, in those situations it's too dangerous to turn around or to slow down for anything--all gear needs to be stowed and secure, also so you won't trip over it. Get all that done before you start running and before the wind is up. Stop fishing, stow the drinks and focus. Get your crew focused.
Before starting a crossing like that, amend your float plan (you did leave a float plan, right?) by calling someone on shore and let them know your location, direction and circumstances. And more important, call them back when you are ashore!*
At 50 mph winds and a 20' lake boat, I'd go to a cove even if shallow. This is why you carry a strong anchor, properly rigged.
Wind usually drops an hour before sunset and stays down for a few hours afterwards (although I am not experienced in desert lake microclimates so I may be wrong).
Draw from your experience; what was the water like before it got really gusty? Small ripples and ripples on top of the waves? Your clue to bolt immediately, not to wait and see what happens. Sure, there are some systems that have little warning but even line squalls have signs in advance. I learned a lot about surface air when I learned to sail; I use it all the time in a motor boat. But even the most casual pleasure boater has a responsibility to learn to read weather like a sailor. Trust your senses; I've felt the hair on the back of my neck rise with an impending hurricane.
Glad you made it. Great adventures in boating are born from experiences that occur not by choice. I know I've punched out a couple of my nine lives out on the water.
*I once had to scramble a boat at night, winter, in seriously bad conditions to go look for someone who made it in OK but forgot to call when he got ashore (I was secure on an island). He truly risked our lives for nothing.