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.
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 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.
Endfed antenna theory