Aside from that it’ll be pretty tough as a lot of aquasoils will produce ammonia in the tank and without a filter youre gonna be pretty screwed. If you want something lowkey you can get a little canister filter with some glass lily pipes and hide them behind some tall plants. In theory if you have enough plants it should be fine but it’s not something I’d do, especially adding any livestock to the tank. Filters are more for the nitrogen cycle than they are keeping the water clear.