Role Preference Slider

I almost always queue up as mid and support, and recently I've been super grateful that I get my main choice the vast majority of times, and only really get dropped into support every now and then, usually if someone dodges a queue. But more recently I've realised I would like to play more support games without queuing up with it as my primary, so I had a thought-

What about having either a slider (either a linear dot on a line between two roles) or a matrix of the 5 roles you can show preference for?

Solution one, you could pick jungle and adc and then set it as a 50:50 preference (or any leaning you prefer, up to, say, 90% either way) and provide more of a fill role when you want, vs the way the system tends to give you your initially preferred role at high preference at all times.

The second solution, I could queue up and get any of Mid, Top or Support with equal chance, be unlikely to get stuck with ADC, and know I'll never get queued Jungle (an outcome which in my case would require me to beg someone vaguely competent at the role to swap with me).

Thoughts / other ideas on a slider / matrix based role preference?