You are underestimating Tiagra level components. They are tough and durable. I changed my cassette to an 11-34 and put on a 24T ring in the front and it works fine even though I am pushing the outer limits of what Shimano says is possible. So I have a range from near-MTB low gears to a road bike level 52-11 high gear. I'm quite happy with it.
Get an Aurora, put on some Schwalbe Marathon tires, a Brooks saddle, slap on a smaller granny gear, and hit the road.