Not sure I’d feel comfortable putting something underneath, and not sure it would look good. I’ve got my eye on something like this but probably will spend a little more than $20 for the peace of mind.
If you don't want to mount it and don't want your center speaker as a stand, you can get this stand for your tv: https://www.amazon.com/dp/B07KFD7QPZ/ref=cm_sw_r_wa_apap_HHxlDiNE1CPyU
It works for me!