If you haven't grown bucephalandra you may find them more difficult than you expected. Between the fact there are so many different species with seller-specific names, and the fact they are less studied and familiar to the hobby, it can be difficult to find concrete evidence that a particular plant will do well in a given tank. I have a friend who has very high quality show tanks that he enters in competitions, and he's agreed that bucephalandra can be a tricky bunch, even with good lighting and CO2 levels. I'd pass on them unless you specifically find someone here on the forums that is selling one they are already growing in low tech conditions and they look healthy. Can't beat that.
Anubias are very slow growing, but man are they versatile and easy to please. You can't go wrong putting them in a low tech, and there are many types that are well known in the hobby, can't speak well enough about anubias for low tech.
Rotala can be a bit more tricky. It's generally an easy grower, but it does best with stable water parameters, good gas exchange (which that skimmer will help provide) and adequate water column fertilization. If you plan on regularly dosing water column ferts it should be fine, but will likely be the first plant to show problems. Honestly I try to keep one plant in my tank that struggles but grows fairly quickly. Two reasons for that. 1) It can teach me what I'm missing (like lately I learned my water parameters shifted unexpectedly because my tap water changed dramatically in a few weeks. My rotala stunted and my fish looked pale, so I knew something had changed, thankfully I know what happened now, but I might have missed it without watching things closely. 2) if something is wrong in a tank, a faster grower that is more sensitive will help me know WHAT is wrong by how it behaves. They show deficiency signs fast enough you can correct them before your anubias leaves get pin holes or get warped from not having adequate fertilization.
Crypts are also slow growing but very easy. Feel free to throw them in, just keep in mind that they grow baby plants a few inches away (2-4ish) when they are growing healthy and happy. They aren't dense and bushy very quickly, so don't expect them to fill a space visually unless you give them a few months. They can also get huge over time, but this takes months, even years depending on the set up and species.
If you're going for bulletproof plants for low tech, dwarf sag, and valisneria do really well. They spread via runners and can be a real pain to control as a result. But that's the benefit for them too. You'll never run out of them, and they grow healthy and fairly quickly even in lower light set ups.
Personally, with the hardscape you have there, I'd go with anubias, crypts, and microsorum (java fern species) maybe bolbitis. Some people can't easily grow microsorum species in low tech, but if you can get them to do well they can be thick, bushy, and hardy. You can get a few of each of these that are fairly different from each other to provide variety. Anubias nana petite is very small and round in leaf shape, while anubias lanceolata makes 3-6 inch long leaves that are fairly thin, and those are just two examples. Microsorum comes in at least 4 different leaf shapes as well. Bolbitis (mini or regular) has a very fine leaf texture to contrast.
Lastly, if you want to go with stems, rotala and ludwigia 'red' are a decent way to introduce color. Being that they grow a bit faster than the other plants (valisneria and dwarf sag being excluded) they may help to keep down algae.
You considered trying Monte Carlo, and if you have an extra $10 to buy a pot, why not try it? It can do well in low tech provided that your set up can provide some natural CO2 generation.
To provide a liiiittle extra natural CO2 you'll want to consider substrate. Soil (like from a garden) can help provide this, but that depends a lot on your soil composition which varies greatly from place to place. I have a friend who had a very successful low tech by using Miracle Grow Organic potting soil (careful to avoid any product that has manure in it, that can leach a LOT of ammonia sometimes) and capping it with pool filter sand. As the organics broke down and the peat moss lowered ph, his plants did much better than I would have expected.
My personal recommendation would be to try putting a small bit of soil in the bottom, say the bottom inch, mixed with potting soil. Then cap with something like Aquasoil, but that's just my two cents. Or given how long this post has become, my 10 cents.