Clip Studio has perspective rulers that are pretty great along with general rulers and stuff, but you can do multipoint perspective and all lines will be drawn on that perspective. I believe they recently had a sale for the program. There's no need to get the much more expensive EX version, all of it comes with the base version.
On that note, if you decide to get the EX version buying the base version and then an upgrade is a much cheaper way of getting the EX version than buying it outright.