I would say no. They are meant more for horses jumping larger fences, and even then I show in 3'6+ class but my mare doesn't tuck her legs tight to her belly therefore I don't usually use. But if you move to 3 foot plus and your horse is an under tucker where he would hit his somatic you may consider.
Belly guards are very helpful for horses that are jumping very large fences and really aren't needed below 4'0. At 2'3 your horse isn't tucking up into himself so much and really in the air for a long period of time.
I would say save your money and stay with a regular girth.
If your horse has issues for some reason with hitting his chest you can, but there is really no need for most horses at that height. They just aren't tucking their legs up enough to have any issues.
Hope this helped!
I wouldn't say so but I like to have then there anyway because 1. They do look good and 2. If they were to take and arkward stride and lifted the front legs strangely then you want it there just in case. It's really up to how your horse jumps
Hope this helps!! :)