It might be possible one way or another, although I used separate gfx cards. You might find a different x server that lets you do it using a single card. I suggest getting an extra hard drive, install grub so you can dual boot, install the experimental OS on the extra hard drive and start fiddling. I also dual booted different OS in order to experiment with machine learning when the kids was sleeping, as I got multiple gpus, although the old ones where crap it was a good learning exercise.

Modern GPUs aren't constrained by the number of ports. You can use DisplayPort MST (hubs) to output multiple displays off a single port.

But most GPUs are limited to being able to run 4 displays. Except some AMD Eyefinity can do 6