Thanks for the suggestions Matt and Tim! CO2 and fish health is a complicated topic. Species no doubt differ in tolerance according to their natural habitats, the research on the area is sparse and unfortunately you can't ask a fish if it's bothered by the CO2 levels in your tank. But based on my limited research on the area and applying the precautionary approach I've decided that I'm not going to use CO2 for now. Everything else being equal it's safe to assume that a lower CO2 concentration is less stressful for fish compared to elevated CO2 and right now I'm not bothered by slower growth and having a limited pool of plant species to choose from.
Plantwise I ended up with a pretty extensive list as usual..
Background:
Hygrophila siamensis 53B (we'll see if I can keep it looking fresh, if not I'll switch it out with someting else.)
Vallisneria nana
Crypts: albida 'brown', x willisii, wendtii green
Epiphytes: Anubias nana 'petite', Microsorum 'trident', bolbitis heudlotii, some unidentified water fern from Borneo (couldn't resist the exoticness), Bucephalandra 'wavy green', 'braunrot' and 'Lamandau mini red'.
also ordered a few Limnobium laeviagatum to suck up nutrients in the beginning.
The crypts and vallisneria would probably benefit from not using too soft water, right?