Lightroom :: Crop As Saved Preset?

I am trying to find my way, of how to submit my photos to the external lab for printing. Print module is kind of useless for me - the page setup is printer driver dependant and none of my installed printer drivers allows me to define borderless print and so LR does not allow me to set margins to zero. I think, that such desing limitation is pretty strange, especially if you just want to print to the jpeg file.
 
So - then I moved on to the crop tool. What a bunch of inconsistencies and design limits:
 
- LR seems to use some kind of catalog dependant storage, instead of just some for e.g. custom XML or other kind of list

- LR mysteriosly remember your last 5 settings. If you do a mistake, you need to reenter all of them again

- you can't even name your custom ratio settings - that's imo pretty much insufficient

- I need to set precious ratio setting for the Noritsu machine, so that I get exact resolution. Good for two of my settings, but when I try for my 13x18cm (2268 x 1625 pix), LR deletes my custom setting and marks 5x7 for me. But it is off by 10 pixels on one axis! Some strange rounding and matching was applied, but I can't it set exactly to what I need. Why does LR mess with what I want, if I select custom ratio?!
 
So I thought, that I might make a preset. I noticed, that when you copy setting from an image, there is a crop section. But - exactly the same dialog, which allows us to save settings, does miss a crop section. What a bummer! I found xy requests, where ppl were asking for the functionality few years ago. I am very negatively surprised, that it was yet not granted for implementation, especially as some of crop tool facilities are pretty arcane at best.
 
What I am now thinking about is to prepare three model images, make separate folder for them, and use them as a source for the cropping setting to copy from, but of course I would like the crop functionality to be enhanced/fixed.