I am interested in operation primarily on 160, 80, and 40.

I have space for a full-size dipole for 160 but I cannot get it up
very high, maybe 30 feet, higher than that only at great expense and
with great difficulty.

I will likely put up a 160-meter dipole at 30 feet and feed it with
ladder line and a tuner, and use it for NVIS work on 160-40.

For DX, though, I'm wondering if I will be happy with a vertical such
as the Voyager DX from Gap Antennas, or if I should bite the bullet
and go to the expense and difficulty of getting the dipole up 60-80
feet (which still won't be very high, compared with a wavelength, at
160 or 80).

What's your advice?