Yeah, I really doubt you'd get anywhere near the maximum cycling running it only up to 90% SOC all of the time. Plus, that'd just kill your range, since you'd only want to run them to a maximum of 75% Depth of charge to avoid killing the cycling life. That gives you a pretty thin range to work with.
I know that with lead batteries, it's recommended to never get them below 75% charge, and to always bring them right back to 100% ASAP for full cycling life.
Will your laser be turret mounted? Or sticking out of the hood or door or something, that might be quite the aero drag.