Big Bend NP

Does anyone have experience camping in the Chisos Basin of Big Bend NP? There is a recommended limit on trailer length of 20 ft for the road into the Basin but I wondered if this is a strictly enforced rule or can be fudged a bit for the smaller models of TM.

I don't yet own a Trailmanor but they sound great. I hope to be in the market soon.

Thanks.