it will boot fine with or without a battery,with the rare exception scsi vram is scrambled somehow,but i've only heard one case of this in 20 yrs.
If you dont mind a external card reader, what you can do is install it in a old external floppy case and build a scsi cable to hook to the back of the 3k scsi port. makes for a pretty slim external card reader solution.
@tcmslp Getting time from internet works very well on amigas with badly damaged boards that are not practicle to add a battery. Its more accurate than onboard time in alot of cases.
They draw very little power and run cool,so no worries the card reader will get too hot etc.