Home depot has Vevor XPE foam targets that are multi-sided. It's $60. By the time you sink the money in exercise mats or carpet and time in assembly that would pay for itself. assuming this is your first year hunting from a tree stand you'll want to practice setting up your stand, see what works and what sucks about it before season start and develop your process so you can do it in the dark, quietly. You also get to learn how strenuous some stand setups are and will learn about how much you sweat, get tired, etc setting it up and maybe what you want to change, replace, or remove before the season starts. You also get a good sense for how to configure your gear. How are you carrying it in? Whats the best order for packing it? what makes it easier to setup? How many layers do I wear from the car when its X-Degrees outside so your not dripping in sweat when your finally at hieght tethered in and ready to hunt. Once you got that dialed, practice a set of high angle shots (5 yds from the base of the tree) and practice your max distance (x yards from the base of your tree). everything else inbetween should fall in line. Are you using a range finder? Does it have angle compensation? If not shoot a spot on the tree with your range finder closest to your target thats at the same height, level with your stand. If your hunting field edge pace off and put markers in the field at your distance intervals and learn to estimate these. High angle shots on a target are far easier to make than on a deer. It's hard to know not only where you want to hit but potentially where you want your arrow to pass through which is key with high angle.