IM makes a 20 gallon long and a 25 gallon lagoon. I have the 25 lagoon. You should at least consider some Random Flow Generators for your return nozzle(s). I really like the ones from Vivid Creative Aquatics, who's a member here at R2R, and usually available to help if needed.
https://vividcreativeaquatics.com/innovative-marine/
I believe that these RFA's and a decent return pump would be enough flow for a softy tank, and likely provide enough flow for your anemones.
You could also look into circ pumps like the EcoTech VorTech pumps that are a bit pricy, but they keep the cables out of the tank, and arguably offer the best look for circ pumps. There are some less expensive Chinese knock off pumps available from Jeabo as well.
Good luck!