Dipole at one half wavelength elevation (left),  shows lower take-off angle,better for DX. Left image is same antenna at a quarter wavelength elevation, or less, typically better for local (NVIS)These are simulated images , using, 4nec2 free software by Arie Voors.

https://www.qsl.net/4nec2/

A 40m DX antenna would require a minimum of 60ft(~20M) elevation. Vertical antennas can accomplish this a little more conveniently for smaller lots except for the large number of ground radials required.

I/4 ground plane vertical

Shortened vertical dipole

I have gotten good results with an endfed antenna mounted as vertical endfed dipole , requiring little or no ground radials. This page by PD7MAA, gives some basics for design and details for building your own.

http://pa-11019.blogspot.com/2012/04/149-transformer-for-endfed-antennas-35.html

Endfed antenna theory

http://www.aa5tb.com/efha.html

Gary ae7ov