So if we use the garden hose to bring the boat up to temp we can shut it down and put the hose into a bucket of antifreeze and it will suck it in and we can run that into the system?
I do not recommend this method, as you end up with a diluted mixture in the block, thats impossible to predict its protection level. A good portion of the A/F is going to divert right to the exhaust. What does enter the block, will mix with the water. You wont get a wall of A/F that pushes the water out.

Drain all the water first, then induce the A/F if you feel its still needed.

As to corrosion protection, that depends on what type marine/RV antifreeze you use. Some are intended for fresh water systems that are 99% plastic and rubber.