You want some overlapp? you want some "virtuell" distance to make it most realistic (like watching through 3 windows) or what do you wanna do ;) Either way you will lose some parts of you composition area when you dont want stretched or compressed ugly stuff ;) so max high (3840) x max wid...
I did this and yes it work like you think it should =) Content Wise you should stick to clear borders and more on the thin side.... A lot can be done with the internal sources and effects.... also slower can be better .... all this things can be adjust quite quck on the fly when you actuall see what...
Any of the amazon one's should work. I would also suggest throwing an EDID spoofer/cloner inline though as some of those chaper ones will disconnect your second input when input 1 is active. The spoofer will hold the link to your machine regardless of what input is active. I Think you missed the re...