Comrades,
The top of a hill -- unless there is some overpowering tactical reason to be there, or some really great cover, is a bad place for any unit, infanry, armor or vehicle to park.
Tankers are taught to avoid hill tops like the plague. For one thing it means that anyone on the map can probably see you, and secondly (and less significantly for game purposes) it silhouettes you against the sky, which means anyone at a lower elevation has a BETTER shot at you.
Reverse slopes can be interesting places to hide and ambush the bad guys for a close range knife fight, peeking over the hill can be very rewarding if you do it right. forested hills can be good places to hide... But sitting up there in the open is an invite to get splattered.