functions as template argument, plus variadic template argument

I'm writing a generalized function wrapper, that can wrap any function into a lua-style call, which has the form

int lua_function( lua_State *L)

And I wish the wrapper function is generated on-the-fly, so I'm thinking of passing the function as a template argument. This is trivial if you know the number (e.g, 2) of arguments:

template <typename R, typename Arg1, typename Arg2, R F(Arg1, Args)>
struct wrapper

However, I don't know the number, so I beg for variadic template argument for help

// This won't work
template <typename R, typename... Args, R F(Args...)>
struct wrapper

The above won't compile, since variadic argument has to be the last one. So I use two level template, the outer template captures types, the inner template captures the function:

template <typename R, typename... Args>
struct func_type<R(Args...)>
{
  // Inner function wrapper take the function pointer as a template argument
  template <R F(Args...)>
  struct func
  {
    static int call( lua_State *L )
    {
      // extract arguments from L
      F(/*arguments*/);
      return 1;
    }
  };
};

That works, except that to wrap a function like

double sin(double d) {}

the user has to write

func_type<decltype(sin)>::func<sin>::apply

which is tedious. The question is: is there any better, user-friendlier way to do it? (I can't use a function template to wrap the whole thing, coz a function parameter can't be used as a template argument.)