One trick I've been using fairly often to ensure integer coordinates is to divide my shape into a uniform grid that can then be stretched to the actual size. Then you can use a combination of the SVG's size, viewBox and preserveAspectRatio='none' to stretch that to the full size. Have used that frequently for flags, e.g. https://commons.wikimedia.org/wiki/File:Flag_of_Biliy_Kamin....

But indeed, when using Inkscape for exact geometric work, you need a lot of care and in many cases editing the file by hand is easier.