Three ideas: Broward College offers beginning and intermediate sailing classes. But with your European licenses you may know more than their instructors. The South Dade Marina (farthest south place in Dade County) and the Key Lime Sailing club in Key Largo are hangouts for trailer sailors...
I'm a cynic, but one with experience. That experience tells me that half of the capacity of any battery-powered system is written in the engineering department. The other half is written in advertising/marketing.
The "easy" way to extend those cables is to get a same-diameter battery cable the length you need. Then bolt the two together with stainless or bronze bolts, nuts and lockwashers. Tighten up good and tape with rubber tape and then vinyl tape. Finish with a coat of clear lacquer so the tape...
My boat also came with the stainless prop tubes, but I added hydraulics because both my wife and I weren't strong enough to raise the original. I suspect that Roger only sold that model to Paul Bunyan.
S/V Sand Dollar
A modern charger that has automatic equalization is a very good idea. If you REALLY want to do it by hand, here is the info you need: Leave the battery in its box or put it in an old cooler. Cover it loosely with a thick rag or old towel. The objective here is to contain flying acid in case...
I am guessing the video on the Haulover Inlet was intended as a joke. If you do try it, watch out for two BIG sandbars just inside. Shallow enough to ground a Macgregor 22.
S/V Sand Dollar
(now u know where the name came from)