You can put an aerial inside the car, but be prepared for poorer reception as there will be metalwork etc between the aerial and the signal source. This is why an aerial is normally mounted on the highest available part of the car.
all that should stop reception would be the roofs canvas?
And the metal frame. The only way to find out is try it.
On a side note, aerials are normally a tuned length for a certain frequency, or range of frequencies, so running a length of wire may be a bit hit or miss.
I would tend to go for an in-car amplified aerial.
http://cgi.ebay.co.uk/CELSUS-SCREEN-GLASS-MOUNT-AMPLIFIED-CAR-AERIAL-AN7920_W0QQitemZ200326876841QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item2ea4698ea9
What about the area behind the windscreen trim?
at the top you mean mate? where the rear view mirror is? i thought about that
depends how hard it would be to wire it in there... cant really be bothered removing all the dash again lol
To get the trim off all you do is unbolt the sun visors and pull it off.. it is just held on with clips. Theres a bit of space behind it and the windscreen surround itself I think is hollow and if I remember rightly has holes to access the cavity behind the trim!
i have no sun-visors so should be simples lol...
its getting the wire from the head unit to the cavity that may be tricky
Might be able to get up into the void with some coat hanger wire maybe from under the steering wheel area.