Over Stressed Engine?

I have a '97 Tracker/Vitara (Suzuki componants) with a 1.6 motor. I am going to be making a thirty minute drive up a steep mountain road on a daily basis. For most stretches I have to stay in second as it will bog in third. I've running at 3000-3500rpm. At the upper rpm the engine sounds strained. Is it? The tachometer goes to 6000. I'm wondering if climbing at 3500 for that leignth of time will cause exessive engine wear over the long term. And how about the return trip using a lot of engine breaking to give the breaks a break?