Newb Substrate Help. Dirt+BlastingSand + ?

So im about to start my first planted tank [with eventual RCS].
Ive done hours of google research and I think im ready to begin. I want to follow the walstad method, but also really like the larger top substrates. I like the idea of the heavy black blasting sand holding down the soil, but was wondering if it is feasible to ad soming larger on top. I like the look of Eco Complete but suspect that would be over kill. Is there anything that is similar that wont jack up the balance of substrate. Something like. 1in Soil, 1in Blasting sand, the 1/2inch of a larger black substrate?