I do it all the time (albeit not at HOU). Don't sit in the back of the bus, try for rows 1-5 and you'll be in good shape. It's been a couple years since I've been at HOU, but I seem to recall the WN terminal is compact enough to make a quick connection. I remember it being a really nice terminal.

If you do miss your flight, they'll confirm you on the next flight with seats open. They will put you on the standby list if flights ahead of yours are full.