I bought a small one for the RV. It works just fine.
The larger ones are a REAL big drain on electricity and create a LOT heat from the unit. You really don't need a honkin big one for the RV.
When I went to buy one from Lowes one entire shelf was empty where the smaller ones would have been.
I talked to the manager and he said it was Snowbird RV season when they all head back leaving RV's and/or Winter homes behind needing de-humidifier's, and every year the small midsize dehumidifiers all sell out in one full sweep! So there's your recommendation from the Snowbird crowd! :C