I have used verticals on the ground with hundreds of feet of wire under them and on the roof with short radios such as an R7 has.  I'd always prefer the verticals to be above ground as far as I could get it but a ground mounted vertical can do some amazing things.  Once I got a tower tall enough to hang various wires such has quarter wave three-way switchable slopers on 80 and 75 meters, or 40 meter loops or 40 meter center fed dual slopers for directivity, I found such wire antennas excellent performers.  Inverted Vees are a good antenna, generally, but as with any antenna, the higher; the better.  If I had my choice of verticals or wires, I'd take flat top dipoles any day.  They work better than inverted vees and rotatable dipoles really do out perform the verticals and wires and from just about any level; meaning 30 feet on up.  I'd even put up a rotatable dipole at 25 feet verses a vertical ground or roof mounted.  Most people just have never experienced how well a flat top dipole radiates, even if it is made of wire, and if you can put up a rotating dipole for any band, it will out perform any inverted vee.  Just one man's experience.  You can buy triband or 5 band rotating dipoles that work equally as well.  So even if you can only put up a 3 or 5 foot roof mounted tripod with a small AR22 rotator, by a rotatable dipole because they work and at least you get some directivity by making half rotations when need be.  For example, turning a rotating dipole broadside to Europe bi-directionally to Australia and New Zeeland, then turning broadside to South America and Northwest to Japan will improve your signal over an inverted vee at the same height remarkably.  I know because I've tried them at various heights and wire configurations.  Once I got, for example, a 40 meter rotating dipole, I put it up at 30 feet on the side of the tower.  I was getting 1 to 2 S unit higher readings than my 40 meter loop hanging from 60 feet to ten feet off the ground.  I took all my 40 meter wires down and put the 40 meter dipole at 60 feet.  For the first time in my life, I began working Europeans from Colorado an hour before sunset which I had never done with any wire antenna.  The first night, I rag chewed on 40 CW for an hour with a South African ZS station right in the middle of loads of other signals so I was sold on that 40 meter dipole.  There's just something to getting any antenna away from ground absorption.

Phil.
K0NX