In Bruno Marc's book 'Dolmens and menhirs of the Ardeche' we spotted a number of interesting monuments listed in the Bois des Geants along a single track which didn't look to arduous for a non-walker like me!
Not recommended, but I drove up a gravel and bedrock limestone track for as far as I could before the really big rocks threatened to damage our ordinary large family saloon (a Mazda 626). We eventually had to park up and walk through the woodland and scrub which smelled of herbs and hot pine resin.
On the map we saw six monuments marked, though we only found three.
Please be aware that due to difficulties in spotting stuff on google maps, the PRECISE location of each monument maybe out by a few metres - the track that they are on is the right one, however. Please note that the track you need to go up is to the west of the bridge that crosses the combe.