Why not just do it all in FB. I do (almost) all my programming in FB. The AND and OR blocks are designed for booleans, the SEL block is another useful tool when a boolean is needed to select which analog to use in a calculation.
I have programmed whole plants without the need to resort to ladder logic. I find the end result is much more readable and easy to fault find program.
Mind you I haven't used RSLogix for a while (I mainly use Schneider UnityPro) so not sure about there implementation of the FB language.