What you might want if you are considering a marching band harness is specifically a tenor harness. You can easily modify your current operator's console to fit it very easily, as you will only need to mount your operator's console to the part that the tenors mount onto.
Here are some good reliable ones that Yamaha sells. These are not specifically tenor harnesses but you can navigate and find them.
Link.
I recommend
These are what our drumline uses.
Pavan.