No easy way, and also no way at all if you do not jailbreak your future/new Kindle. Keep in mind that probably every new model currently sold by Amazon (Kindle Basic, Paperwhite and Voyage) ships with firmware 5.6.x for which there is no jailbreak method (other then opening up the case and soldering wires to serial pads on the [mother]board).
After jailbreaking you Kindle you have to be comfortable with editing .jar files found on hidden part of Kindle's memory, where margin values are hardcoded. Or wait when/if someone else post .bin installers for your new device and it's current firmware. But first of all you'll be waiting for new jailbreak method (which was reported as found but is still not publicly released).
The location of code responsible for marigins was known for earlier fw 5.x , but I'm not 100% sure it still in the same place for the latest fw 5.6.5. You should probably ask someone with jailbroken Paperwhite 2, Paperwhite 3 or Voyage to check, on this thread:
https://www.mobileread.com/forums/sho...d.php?t=256969
Your best bet if probably asking @ecostin, via PM.