Okay I got the calibre plugin "thing" working. I forgot to check a checkbox the first time. So the K4 can easily run one extra, sideloaded font and you can lessen the margins. This worked exactly as it does for the K3.

I'll have to Google where I got the info, but it was here on MR. I think it was in the Kindle Developers forum. It is pretty easy and quick. It takes longer to find your fonts than to use this method.