Current Thai and Lao immigration hours at Mukdahan-Savannakhet Bridge

I'm planning to cross from Mukdahan to Savannakhet on the evening of Wednesday March 13th. My flight gets in to Nakhon Phanom at 16:25/4:25pm, and a taxi from the airport to the bridge takes about two hours, so I should arrive at the bridge by 7 pm. 

I know that the bridge is open till 22:00 daily, but will the Thai and immigration posts on the bridge still be open at 19:00-19:30? Anyone done an evening crossing there in the last year?

I would spend the night in Muk and cross in the morning, except I have to be in Savannakhet by 21:00 that night for the Savan Fun Fest.

Thanks,