I agree. You almost HAVE to use keyboard for all backing. I play with a group that has two additional guitar players and a sax. Everything else is my problem.

Practice is ESSENTIAL, since your other musicians need to get used to the limitations and capabilities (tempo changes, transpositions etc) of the keyboard. You have an advantage here since you wrote the music yourself. When trying to play covers it's quite an issue sometimes and can cause friction simply because certain tempo changes are almost impossible to achieve...

Make sure you have a decent speaker setup - which includes a monitor speaker for yourself.

Good luck

Jerry