Thanks to both for the quick response. Here's my plan and please let me know whether you think it will work or not:
2.5 G tank with 8W stock light (8 hrs/day), I suppose it's low light considering it's a small tank? I will turn off the lights duing weekend since it's in my office. I hope that will help me control algae.
Substrate: Aquasoil Amazonia, and rocks as decor
Plants: 1 willow leaf hygro (I will cut a branch from my 29 G), as well as bunch of pennywort as background; plus lots of Marsala Quadrifolia and Glosso as ground cover.
Ferts: Excel, N/P/K/S (if necessary)
Animals: RCS, plus a couple of small fish such as white clouds.
I will plant the groud cover and cover them with the soil, and then plant the background as well. Then fill with water and monitor the NH3/NH4 until it drop to near 0 so I can move animals in.
My goal is to have no CO2, no filtration, no water change, therefore a low tech tank. Would it work?
BTW, currently I do have another 2.5G tank in the office, which has plants, same lights (off during weekend), no CO2, no filtration, no heater, 2 white clouds, a betta, no water change. It works really well without any algae, and the fish are happy (or I think so)! The substrate is just plain gravel with root tabs embedded. Being encouraged by that tank, I decided to set up a even more heavily planted (thus "prettier") tank, hence the idea above.