You can modify the tank or the skimmer and use the Tunze 9002, I am not sure a 9001 will fit though. Look at Cadlights foot print as well. Just go to MarineDepot nano skimmer section.
You don't even need a skimmer for that tank. Just do weekly water changes to keep the water prestine, after water displacement, you have less than 20g of water.
Reef octopus classic 1000 or 2000 HOB. We got one for my son's nanocube several years ago and it does great. A little big but it will fit without the intake surface skimmer and output thing.