While this should work on paper, I wouldn't recommend this design. Ideally, strive for a loop-free design. My personal guess - you have 1 to 2 outages per year caused by the redundancy of this design, and probably no outages if you make one switch the core and simply cable both other switches back to only the core.
My personal experience is mal-functions in spanning tree make the network more susceptible to outages even though it adds more redundancy.
As you indicate, you could get a pair of MS210-24P switches and hardware stack them, and dedicate them to being core switches.