If you want low maintenance, why not just do shrimp only? They prefer cooler temperatures anyways, so I doubt you'd even need a heater unless your room gets really cold during winter months. The light will add a little heat itself, especially on nano tanks. You may even be able to get by with placing a heat mat under the tank to add a little warmth during cold months. There's also the whole predatory thing with tetras and baby shrimp, if that matters any. Not many fish will pass up an opportunity to feast on some little soft shrimps, except otos.