The casino has been destroyed, but the Oasis RV Parks is still there. The RV Park is now operated by the CasaBlanca Casino.
Oasis Resort Casino
We were in Mesquite recently - stayed at the Oasis Casino RV Park (a real sardine can park, but the price was right at about $16.00 per night). We noticed a lot of free truck and RV parking available at the Oasis (across Business 15 from the casino at the west end of town), and at the Eureka Casino (east end of town) behind the motel buildings, although we didn't stay in the free lots.