Rick wrote:
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?
Hi Rick,

As someone has said get a copy of ON4UN's Low band dxing..
I would not particularly recommend the Gap Antenna for Low Bands.

Than being said if you and put out a decent radial system for dx
Transmitting anyway I'd say you want some sort of vertical.

Why not try a Inverted L. Try to get as much vertical as possible.
Base tune it with a matching network- The SGC line works well for that
application. you can read more about Inverted L's in Cebik's write up at:

http://www.cebik.com/wire/ltv.html

Good Luck
73, Dave Kc1di