Template specialization in presence of variadic templates

I have a struct foo as so -

template <typename T, typename...V>
struct foo;

I want to specialize this struct when T meets a specific condition, namely when it inherits from a class bar.

I know how to write this condition using std::is_base_of<bar, T>::value and combine it with std::enable_if.

Without the variadic template I could use an extra template argument (void) and default argument like so -

template <typename T, class Enable=void>
struct foo {
    // default implementation
};

template <typename T>
struct foo <T, typename std::enable_if<std::is_base_of<bar, T>::value>::type> {
    // Implementation when T inherits from bar
};

But I cannot combine variadic templates and default template argument because both need to be the last template arguments.

Any suggestions how I can implement this specialization?