With that size of a tank and cichlids, I would go with a small group of jaguar catfish or, at the biggest, a lima shovelnose. Hoplos might work out great as well.
Unless you plan on getting a much larger tank within the next year or so, a TSN or RTC is way out of the picture.
Unless you plan on getting a much larger tank within the next year or so, a TSN or RTC is way out of the picture.