The greenery will always distort, but you're right, the distortion will be less as you increase the height of the dipoles above the greenery. You get some reflection. You get some polarisation effects as well, which may or may not be important depending on the transmission mode and the path.
Get thee to a library and put in a request for
Radio Science, Volume 17, Issue 5, pages 1027–1036, September-October 1982, which contains a paper:
Brown, G. S., and W. J. Curry (1982), A theory and model for wave propagation through foliage, Radio Sci., 17(5), 1027–1036, doi:10.1029/RS017i005p01027.
Or measure the RF power many wavelengths away, at various antenna heights.