Salt water + brake, suspension, exhaust components and whatever else is back there vs. find an easier way to launch, I’m hoping for suggestions on the latter. Especially if anyone has tried different ball drop heights.
Just an FYI, in Wisconsin they use the salt brine from the cheese factories and spray it on our roads. Then when it actually snows, they cover them in salt. Salt water on your tires / brakes / exhaust ain't got NOTHING on what we put up with for 8 months of the year. Your vehicle will be fine.
To your issue with unloading, you have to get the boat floating or, as already stated, you've got all the weight on the bunks. Even if you can "power unload" it's not good for the gel coat to have that much friction with your bunks.
I would NOT recommend a liquid roller until you can get your unloading routine down. Sprays might work great, but if you brake too hard launching, or pull out too hard recovering, and forgot about safety chains and winch straps (happens to the best of us), your next forum post will be "how I launched my boat 20' before the edge of the water..."
Next time you launch try this:
1) Before ramp: cover off, batteries on.
2) Back down to launch. Stop before back of boat is at water's edge. Unhook your transom straps. Hook up your dock lines and fenders. Double check your plug.
3) Back the boat into the water - watch your mirrors as you put it in. At a certain point AFTER the fenders are covered in water you'll see the boat "pop up" and indicate it's floating.
4) Stop vehicle, go back and unhook safety chain and winch strap.
5) Back vehicle up maybe another foot or so and the boat will lightly float off the trailer. At this time it can be controlled by your dock helper.
6) Let the boat float back and clear of the trailer, pull your vehicle up and out of the way.
I would say that I've never head to put my rear wheels any further than a foot or two from the edge of the water on the ramp. Recovering I might go a little further in depending on how sun baked my brain is by the end of the day. If you're having to drive your vehicle tires 4-5' past the water's edge at the ramp, you should find a new ramp.
One last edit: Your barking up the wrong tree with your ball height assumption. Lowering your ball height at the hitch will only require more water to float your boat off the trailer. Raising it would help, but moving your trailers weight distribution with a higher hitch could severely complicate your towing safety.