Stereo/mono guitar selector box DIY?

In my ideal world/while overthinking things I cooked up an idea for a selector box that would have two outputs (one to my Mesa rig and one to a DI box/FOH for the piezo Signal) and the following inputs:

1) Stereo input for JP15 with a switch to either merge the signals to the amp out or separate them into magnetic and piezo out.

2) one selectable input for cable connection to my strat/backup , magnetic output only

3) one selectable input for wireless system, magnetic only

So these would be 1,2 OR 3 – but 1 having two settings (magnetic and piezo spilt to the two outputs or merged on the magnetic out).

Could all this be done with a passive box or does it require buffers, relays, etc.
Anything commercially available with these or most of these features? I like the Lehle stuff but I don’t think there is one A/B/C box that would do this, especially the stereo in spilitting options.