Bruce,
The problem with the mag-mount antenna is the cookie
sheet isn't large enough to be an effective groundplane.
Adding a couple of 9 feet wires to the cookie sheet would
help a bunch. They don't have to be entirely straight,
they can be bent around to 'fit', just so long as they are
not bent back onto thems selves.
A dipole antenna will work. If you hang it horizontally
it will be horizontally polarized and you will 'loose' a bit
of signal strength. Hang it vertically, or like an "L" and
it will be vertically polarized and should 'hear' a little
better than the horizontal way.
No indoor antenna will ever work as well as an outdoor
one, unless the outdoor antenna is kinda doggy to start with.
But, an indoor antenna is certainly better than none at all.
It doesn't hurt to experiment and it can be as much fun as
talking to people. Give the dipole a shot, or add a radial
(9 foot wire) or two to the cookie sheet...
'Doc