Rear hydration system

Dear triathletes,

I am looking for a rear hydration system (behind the saddle), unfortunately I am having a particular saddle (photo attached), with monolink fit.

Can anyone advise on a compatible rear hydration system for this kind of saddle? I have checked with x-lab and profile design and they don't seem to have anything for this kind of saddle?

I look forward to your comments.

Many thanks in advance,

Regards,