Hi Bad Nav,
Maybe this will give you an idea.
Our airfield is 4800ft. With the QNH during December we actually had occasions where the Density Altitude was 8500ft and higher.
I fly a 503 Windlass with Aquilla II wing. Now this plane is excellent, it's quick (I keep up with the 582's and I'm even faster than some of them), but it lacks the climb rate.
Flying alone, no problem (I weigh approx 75kg's). When my wife wants to join (obviously can't say her weight, but together we weigh 130kg's

), I need too carefully watch the amount of fuel I add as well as the QNH. We have flown together at DA's of 7500 - 8300ft. The climb rate is very low and the aerie's engine works really hard, so I avoid long trips.
I have also taken my brother-in-law for a flip at a DA of 8100ft and he weighs 92kgs, never again. He will have to wait for winter before I take him with me again

.
My biggest concern with my plane up here is that I fly on the margin. There is no room for error, especially with a PAX. I have one chance to land the plane, no way that I will be able to do a go-around (mainly cause of our obstacles and surroundings at the airfield).
Hope this gives you some kind of idea.