Slats are a great option but they do need to meet a specific set of standards. If you are using a 3rd party base, those slats should be the same width, flat and spaced equidistant from each other, not too far apart.
Keep in mind that Leesa mattresses should be set up on a flat, rigid surface. Some slats are arched/curved/bowed or flexible, which will change the way a mattress is intended to feel and perform. Over time this can cause damage to the mattress and disruption to your sleep, so be sure to avoid those specific styles of slats.
Using those types of slats with your Leesa mattress will void our limited lifetime warranty.