I have a cable lift standing on the lake bottom. With this type of lift you only have so much travel and depending on the lake level changes you are comprimising for one or the other..
So my ideal setup is everything out of the water this would include the cross beams... this is at the lakes highest point but the outdrive fully down is in the water at this point so it takes a bit of trim to get it out of the water.
Just had my lift guy here 2 weeks ago for some service. Before he left he showed me some slight pitting of the I-Beams. He strongly recommended raising the lift, including I-Beams, above normal high tide level to prevent damage from electrolysis.
Had the lift 4 years now and only raised it enough to keep props out of water before now.
I think you can see how high mine is in my sig picture. I keep the I beams out of the water. I lift mine as high as possible. We have no tides on the Tennessee River but I have had water 2 feet over the top of my decking planks (but only once in the last 7 years).
Sorry, in my picture I have the boat lowered enough to get the AC intake into the water.
Depending on how long it will be out of the water we raise ours (on the TN river) to where the I beams are a foot or two out of the water so that any waves can't hit the I beams and rock the boat.
If the weather is bad or it will be a while before using the boat we take it up as high as we can get it towards the roof to keep it out of the weather more.
During the winter when the ground is dry below the boat we keep it as close to the roof as possible. Often the I beams are 5 feet above the walkway (with another 7 or 8 feet to the ground below that)