My local club runs on a salt water lake, none of our models have developed issues with the salty water, remember to just wash down the boat with fresh water afterwards re-oil or grease the shafts and your good to go, there seams to be a very bad stigma that salt water is the downfall of many model boats, although its not totally untrue as it can cause premature ageing of the model but on the whole the technology is much the same as a real boat and yet some sit in the water for years on end with only a new anti foul coat every few years.
Remember the models are in the water for only a few hours maybe once, twice a month on average, now unless you have a capsize or sinking i can't see how salt water would cause issues with any extra feature such as a working radar or wipers , providing you clean the model after use as good general maintenance.
This does not apply to lighting as bulbs do blow, the only issues with any model that generally occurs over a period of time is 'black cable' where the water/damp/condensation may have built up in the wiring causing it to become brittle and break, or get hot and make the model sluggish if its a motor wire. It can also lead to battery damage, but this is a common issues with all boats.
Also be aware that its not everyone preference to have 'lots of features' on there model(s) but some do , its a personal choice of the builder, some people like myself enjoy it when there's something to add or fix on a model, keeping not only the model alive, but showing the changes over time, not only in the model but your own skills and creativity.
These 'extras' are usually pre-planned during the building stage and i would hope that many allow access to parts should something go wrong, allowing for a relatively simple repair with out damage to the model.
Remember your building the model for yourself no one else so don't get drawn in on what others think about your extra feature's or there 'lack of' if you want wipers and radar then go for it, me personally i like the extra features, it not only add's character to the model, it looks more realistic, and shows the time and attention you took to improve on what otherwise would be a simple model.
