Traverse an expression tree and extract parameters

I'm writing a kind of a mapping tool. I have a method that looks like this (simplified):

   public void RegisterMapping<TTarget, TSource>(string propertyName, 
                                                 Expression<Func<TSource, object>> memberMap)

The memberMap is an expression defining how to transform a property from TSource to TTarget. For the business logic, I need to extract all references to properties of TSource from it. For example, from

x => x.Customers.Where(c => c.Orders.Any())

I would like to get Customers, and from

x => x.FirstName + " " + x.LastName

FirstName and LastName (could be as string[], PropertyInfo is trivial to convert to).

How would I do this? My first approach was to traverse the tree manually, checking the node type and inspecting different properties depending on the node type (e.g. Operand for unary expressions, Arguments for a function call) to determine of any of these are a property of TSource. Then I discovered the expression kind list and I gave up -- even if I support only the most common kinds, it's still lots of work. Then I found the ExpressionVisitor. It looks better, but it's still a lot of work to override the visitor methods and I'd like to know if there's an other option, using perhaps a more specialised framework, before I devote my time to this.