Yeah your dead right there hey. I reckon commit bugger all to that first point and get set up hard on the second. As you pointed out in the other post you made mate, the tele's were a waste of time so sentry/dispenser up straight away and protect that hard. Drop the medic in favour of a heavy and get a good soldier. Flood that second point and use the demo, pyro, heavy, solly combo on point with the second pyro with the engy protecting the turret. The pyro needs to be good at reflecting shit. Heavy can help with taking out stickies also.
I reckon stick with the spy at the start to take out as many as possible. Demo stickies up as per last game but once he feels threatened he retreats to sticky the second point and spam nades. Spy will change back to a defensive class as soon as he dies or we lose the first point. It's all about slowing them down and increasing their time. Beat it quicker and you win... that's the key to a map like dustbowl.
Another possible setup when on attack... everyone puts the sentry in the same spot on the second cap point. But who cares... why take it out if you don't have to... get a medic uber'd up. Everyone runs straight out of the tunnel at the top and we hide from the sentry untill we get to the point. Medic ubers with someone else and runs out into the open while still keeping the uber link. He's now drawing sentry fire... uber'd player and everyone else attacks the point hard and takes down as many as possible... Everyone crouds the back wall out of sentry range but still capping... medic keeps taking fire untill uber runs out but by then he's protected his team mates untill they have hopefully made the cap. This takes out the need for the spy sap on the turret and gives us one more attacking player which we'll need if they have it heavily defended...