On the 2015 Silverback 33rl, 36 ft... Shut off BR valve and two main opposing open. I do this all the time traveling to eat comfortably with the family. We pull thru rest areas at meal time and seek spots where slides can be safely extended. You DO WANT the lighter slide out to provide needed balance at extension. In fact, half the time, I extend dining fully and refer side half way out. The goal is not to weight burden any slide not fully extended. The refer half way allows solid footing OFF the slide and ease of refer use. No biggie.
Just always remember...,full extension before load bearing ( meaning people added weight to the suspension)