Low vents with high vents are far more efficient than an open tops. Misters work great, foggers too but need to be cleaned regularly as they grow bacteria I personally would avoid them as cleaning every day or few days is a pain. Remember humidity is a product of water mass and air flow, substrate and water bowl surface area are the largest factors. Bigger bowls and lager water mass will increase humidity. Royals can tolerate mid 40s with no problems accept during a shed cycle a humid hide can be added at that time to solve humidity issues. High humidity and low air flow is linked to respiratory issues so as VPI say, err or too much air than too little.