Greetings and thank you for your inquiry!

At the distance you're speaking of, I'd recommend using our 4k 40x optical zoom auto-tracking PTZ found here: https://www.securitycameraking.....tz-camera/.  Your Bosch camera seems like it was quite high end when it was purchased, however it certainly seems to be suffering from the TVL540 resolution its chipset is limited to.  I'm going to make an assumption that you're connecting the camera to a recorder over coax/UTP with baluns instead of the optional fiber optic connection it offers; you are going to have to upgrade your recorder as well to utilize our recommended camera.  

A word of note however regarding license plates; between the 40x zoom that should reliably identify footage at about 1400ft and the 8MP resolution providing awesome digital zoom, I think you should be able to capture some plates at that distance during the day.  At NIGHT however, plates are to be honest an absolute nightmare.  When you're not fighting against the running plate lights that light up your plates for the police, you're fighting against IR bounce-back directly off the plate.  There are some very customized settings we use with some of our cameras that can clear those images up, however those scenes are INCREDIBLY dark and capture almost nothing except the plate.  We have a tutorial on our YouTube found here that explains the basic premise behind this setup:

.

I hope this provides you with some food for thought.  Please let us know if you have any other questions.  If you'd like to speak to a sales representative directly please feel free to call us at (561) 288-5258 ext 2 or reach out to us at sales@securitycameraking.com.