Hi,
that mght do the job. Cyclocross bikes usually have fewer gears. Middle aged guys should have 3 rings up front; saves a lot of wear and tear on the knees. There is a relatively new category called light touring. Often these bikes are listed as touring/cyclocross. I have one of those.
But I prefer a light tourer. The real thing will use either cantilever brakes, or standard reach brakes. Either will allow you to mount big tires. If all you are doing in the dirt is Rails to Trails, you can use a touring tire easily. Such tires will be faster on the road. I like about a 28c tire with a kevlar belt. The Rivendell Rufy Tufy is an example. The Trek 520 is not a light tourer.
But it's pretty cheap, and it would out of the box get the job done (might need lower gears, the dealer can handle that). It costs about a grand. If you can go higher, there are some amazing bikes to look at.