RF plate and food rack spacing

[Janis]

Hi there , I’m building my first revers flow smoker . I used the formulas on this forum for all the necessary calculations but now I’m stuck with the spacing between the RF plate and the first food rack ...and the space between the first rack and the second rack ?And if I decide to put a third rack , what’s the minimum space from the top ? My smoker is 28’ high , 24’ with and 60’ long ...the RF plate is 6.7’ from the bottom... thank you in advance