Mentalpause, you got any pictures or details of how that platform is attached to the back of the lift? It seems like the lift has to lift a ton of water when the boat is being lifted up. I don't think that would be a problem for me though, since the lift is rated for up to 24k pounds and the boat is only ~9k pounds. One other thought, would that much wood make the lift float?
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I don't have any personal experience, but member ActiveShack had a 2' wide 'cat-walk' across the back of his lift, and he was able to do all maintenance and cleaning on his 37' Active Thunder; and his stuff was always perfect. Obviously, 4-5' would be a ton better.

The deck frame is galvanized steel, built much like floor joists. The top decking is not wood, it is plastic decking. The frame is attached in a cantilever style approach to the frame members of the lift. I can't remember how much of the deck members bolt along the lift frame members horizontally, but pretty sure it is around 2-3 feet overlap on each side. I'm not at the lake now so I can't take pictures or measure it. but your lift company should know how to tie it in to support the load.

The lift comes up fairly slow with the boat on it, so the water just runs off the sides as it lifts up. It is not a problem. And there is no way that little bit of decking is going to make all that galvanized steel float. My lift is 17K with a 9k boat on it. The last boat I had was closer to 13K and I had no issues with it either. You can easily add whatever size deck you want if you have a 9K boat on a 24K lift.

For fresh water flush...

For each engine.
This....
40615 - Webstone 40615 - 1-1/4" Pro-Pal Full Port Forged Brass Ball Valve w/ Hi-Flow Hose Drain & Reversible Handle

and two of these....
MERRILL MANUFACTURING IBMA125 1-1/4" BRASS ADAPT. MER IBMA125


I just installed these on our boat. Originally had the cheapo Perko flush/check valves. One was already replaced because it had failed and the other was cracked.
Inspiration from here:
Forum gift – winterization valve for Bravo drives Page: 1 - iboats Boating Forums | 660967

You can plumb a hose up to a readily accessible panel with appropriate hose connections. Also, makes for a easy drain on the raw water intake for those of us that have to winterize.

The system Sydwayz described is the simplest, and most elegant. I installed this on my boat years ago, and used it every season to winterize the engines with antifreeze. This same system is going into my new boat next spring.

Just install a simple inline tee before the pump, and run hose(s) to Perko water inlet hose fittings. Attach the hose, turn on water, and start the engine. When done, turn off the water. This reduces the chance of burning up impellers eliminating extra steps to remember enabling and disabling valves. With that said, if you're concerned about the plastic caps on the perko, then you can always install valves. I never had any issues with the caps.

Install the Perko fittings anywhere, or install them in the stern. You could also buy a glove box similar to photo to hide them inside the cockpit, under back seat, etc.

And steer clear of the Perko "automatic", stainless steel, spring loaded valves. I tried them twice, but it appears the springs where the weak point. Eventually temps began to rise as the spring failed, introducing air into the system and starving the engine of sea water at speed.

I agree with Keith. Added these for both motors, as well as genset and A/C, plumbed them directly into the top of each of the strainers. When flushing or winterizing, just close your seacock thru-hulls and your ready.

I like the idea of the added platform on the end of your cradle and agree with mentalpause. I trailer mine and have the flush at each engine. Simple hose plug and play. Times might be tough on dough, but maybe both.. The link to the kit is what was on mine when I bought the boat. I love it......

Hardin Marine - Engine Flush Kit Mercruiser 898235A01

Stay away from the pro flush plastic inline kit. One came apart while out boating and if I didn't notice right away we could have sank and overheated the starboard motor. It ruined our day and my raw water pump on that side. Cheap plastic. Get a metal ball valve like others have suggested. Good luck

I have the Formula Factory setup. Uses a line, but stainless ball valves and brass fitting for each motor. Don't use ANY plastic (it will fail), the ball valves will always stay shut and keep your engine healthy.