c++ Templates to change constness of a function

I am interested in designing a template interface where the const ness of the function and return type itself changes depending on the template parameter. I have managed to do this for the return type as follows.

template<typename T, bool canChange>
struct Changable{};

template<typename T>
struct Changable<T,true>
{
    typedef T type;
};

template<typename T>
struct Changable<T,false>
{
    typedef const T type;
};

template<typename T, bool canChange>
struct Data{
    typedef typename Changable<T,canChange>::type DataType;        
    DataType m_data; //< This makes it const/non-const at compile time.

    // This function will also make the return type const/non-const 
    // at compile time. 
    DataType& GetDataRef(){ return m_data;} 

    //However, it seems to me that I still need a second function 
    //with an explicit "const", which I can't seem to avoid.
    DataType& GetDataRef()const{return m_data;}
};

Can I somehow avoid having two const/non-const functions here at compile time using some SFINAE magic? std::enable_if would have been ideal here but it seems to me that const is not a type and that approach may not work. Any suggestions?