Shorter term au pair?

I am a former host in the USA—we had 3 au pairs when our children were younger, all good experiences, but it’s been awhile. I am looking ahead to next year, when I will be working in another city and traveling home on weekends, leaving my husband alone to care for our two older kids for the spring semester. We are trying to figure out how to make this work, especially with after school transportation and supervision, and are considering an au pair. However, after we move the whole family next summer, we may no longer have the extra space to accommodate someone. I’m wondering about the possibility of picking up an au pair for just 6 months? We are in a remote Houston suburb, and I realize the US requires a 12-month stay, but I also remember that there is some re-matching and shuffling that goes on when things don’t work out, and also some au pairs that want to extend their stays. The agencies I’m looking at all seem to require a 12-mont commitment from families. Are there agencies that allow you to pick up just the final 6 months of one of these au pairs, or a way to bypass the agencies and hire someone directly under similar terms to the agencies? Thank you.