Well I am at the same height too. I generally use a high pitch prop for speed but i am aware of it and compensate by making my takeoff roll longer. Last year I made some comparisons with a couple guys at sea level over in California with identical planes, weight, engines etc. There is about a 3% loss inperformance for every 1000ft altitude or around 17% loss for our area.

I have a F-20 with a Jett 50 and a 9/7 apc turning 17400rpm at around 120mph average which is great here but over on the beach they're pushing 150 mph with the same setup. Have a Shoestring with a G90 getting around 90mph. Don't sound like much but it is here.

Be careful when you ask others for numbers as to where they live at.

Another trick is to go with the higher of the recommended engines sizes. Buying a plane that calls for a .60-.90? Go with the .90