convention dictates tensioner on slackside of belt. What's SD-10? Why 3 speeds?
Grainger sells nice adjustable base. I used one and do not regret it.
Tensioners can allow more wrap, and thus somewhat less tension, for a Nth torque. This can minimize overhung bearing loads, which can be important in some configurations. I bought the parts to make a nice dampening tensioner, and have been lazy by not yet building it.
Alignment is important to savvy.
Tension is a matter to understand. Gates can be very helpful with engineering support in the belt matter. Tension meter is very nice too.
Best, P