Only one of the setups you describe will give you 8 outputs since you'll need one for your UI so unless you go with the RTX Quadro 4000 you'll be limited to 7 HD/UHD without using a display controller.
If you don't want/need warping, It sounds like you might want to use a regular slice with an input mask instead of a Polygon slice. You add points by double clicking anywhere on the outline and remove points by double clicking on the points. You can use linear or bezier mode depending on your needs ...