Looking for Downward Vision system to mount on UAV

Hello everybody,
I have a question which I am having troubles finding out. I am looking for a drone/sensor that has a downward vision system to fly over rough terrain in a fixed altitude. For example I need to fly at 30meters above the trees at all times( ± a few meters is not a big deal). I am talking about the system/sensor that the matrice 200 have. But the reason that Matrice 200 would not work is because I need the payload to be 2.5KG. I have called and talked to DJI technical team and ask them if the could put the same system on the matrice 600 which should be possible for them to do because they have that system already on the matrice 200 but their answer is it is not possible for them to do it. My question is would anyone know anybody that could build a drone with the downward position system and with a payload of approx 2.5 KG?