The County Line Hashplant is my jam, along with the Chem91. But niether of them has much variation as S1's so I don't think the cross would be that fun to hunt through to find a lot of cool stuff. It would probably be fire, but each of those fems is already fire. Why fuck 'em up? Then there's also the fact that both are S1's so I have to reverse something (not happening) or hit it with a random male I know nothing about. Like you, if I do this it will likely be once, and I'll just add to the stuff I have to hunt through dropping beans - nothing beyond that in the plans.
I am leaning towards something I already bought as a Chem91 cross or similar that just turns out good smoke, then popping the rest of the pack. No clue if I'll open pollenate or try and do selections, but selecting males for a one-time chuck seems dumb. And if I do it I won't want to hang on to clones of everything for future work. So likely a big fat orgy of something that grew well and smoked great - mutants and all.