CTAD and even elements of a parameter pack

I'm building a library for random sampling, where a sampler is anything callable with a URBG (basically a distribution, but without the RandomNumberDistribution required)

I've implemented a Mixture<Samplers...> that is a mixture of samplers, weighted.

I want to create one by calling a variadic constructor, alternating samplers and weights, e.g.

auto mixture = Mixture{sampler_1, w_1, ..., sampler_n, w_n};

I've implemented a variadic ctor that correctly dispatches samplers and weights, but it does not work withut a deduction guide...which I can't implement :(

My understanding is that I would need to write

template <typename... Args>
requires (sizeof...(Args) % 2 == 0)
Mixture(Args&&...)
-> Mixture<EvenArgs...>; // this needs to be of the form Mixture<Samplers...>!?

How can I extract only the even elements of a parameter pack, so that I can implement the above guide?

Or can you suggest another technique that I can use to make my desired call site compile?