I've never heard of anyone doing such a device for skid steers. Tractor front loader have a device that connects the frame of the tractor and bucket. Such a device I've seen only very old Russian skid steers , and some Chinese. This device allows positioning the bucket when you raise or lower the boom bucket maintain the same position all the way up or down. In your case will not help even self leveling device. It works only when the arms lift up- when you lower arms - not working. So you needs to make a device that shows the exact position of the bale spear in each moment when lifting and lowering arms.I can not deal with the publication of a picture in the post . Here's a link. http://www.skidsteerforum.com/Portals/57ad7180-c5e7-49f5-b282-c6475cdb7ee7/TTTGallery/balespear/balespear.jpg This device consists of only three parts, is quite simple and very accurate. 3-shaft , 2 -freely rotating rod and 1- fixed rod.Freely rotating rod /2/ will act as a plumb line, and when it coincides with the fixed rod/1/ - bale spear is horizontal.I know that the movement will shake freely rotaing rod. Just try to gliding and everything will work.The challenge here is to find where to mount the device on the bale spear, so to see it consistently all the way from top to bottom.After a little more work you can determine the position of the bale spear without the device. Good luck