BW, welcome. Although careful crossover design and configuration of drivers has given good results in the VP180, as Bruno pointed out, the best arrangement, if possible, is identical speakers across the front. Use a vertical M80 center.
As to height of the tweeters, yes, you may be "over thinking this". If the tweeter would be about 2' higher than your ears at a 12' listening distance, the downward angle there calculates to be about 9 degrees. As Jacques(J.B.)found in his listening test, floor standing speakers typically have good enough below-axis dispersion that listening at that sort of angle isn't a significant problem.
