I am planning to use QRP with a half wave length end fed antenna at 40 m
on a trip into desert country. What range of impedances is to be
expected with the fed end near ground and the other end between
3 and 10 m above ground? Another option would be an end fed inverted V
with the same range of center heights.

Or would be better to use a center fed inverted V with its low
impedance that can be mathed with smaller losses to 50 Ohms?

What would be the best (mimimum loss) tuner for an end fed antenna?

Thanks for your help

Andreas