I was thinking about how I use cyan to mark peat on my map, because the natural colors are difficult to spot while the map is shown.
And one of the obvious solutions would be to have outline or background for the icons, so they can be easily spotted. That would increase the size of the marker and could potentialz block other markers. + what would be the background color so it would actually help visibility?
So a solution: Make the map marker have two choosable layers - first one is the icons already present. Second layer would be optional with larger circles / shapes that could be used as backgrounds is player chooses. It could also contain mirrored tool icons so you can create crossed tools marker in some cases and potentially some other icons if it would make sense in how they can be combined.
So that is it. Just my thoughts on a small thing