This is one of those questions that has been slightly twisted.
If a boat owner needs a car, they will have made the decision for their own reasons and will need to work out how to make this fit their lifestyle, be that cc or marina etc. The debate as whether to have a car is a rather different question to how to manage a car and will have a far wider set of criteria such as cost, location, employment, lifestyle, mobility, interest, requirements, choice of car... this list is almost limitless.
The OP asked about cars and cc arrangements and whilst no car is one way of managing this, she has identified the need for a car. I'd suggest it very much depends on where you are basing yourself (by region) as to how easy it is to manage.
Personally I'd advise against the fold-up motorbike suggestion as it is yet another tax/insurance/licence/fuel cost. It will also depend on the longer term plan for cc e.g. will it be a national tour or is there a node to centre upon (job, family, etc) or is it a 4 mile a day voyage of discovery - whatever float your boat.
I won't be giving up a car until absolutely the end of fuel! I'll just have to work out how to do this if cc becomes my way of life, but the dog walking and random permitted car parks may be the simplest plan.