RE: Flight Camera...which one?
On that small of a plane, your only choice would be a FlyCamOneV2.
There is nothing really smaller and lighter out there now.
You could get away with the weight of a FlyCamOne2, which is roughtly 9% of the weight of the plane.
The DV5100 is better suited to a 5lb plane in the .40+ size range, preferably on the higher end of the scale.
My .60 big stick could handle the DV5100 but mounting it was a real pain... I had to install a camera mount, then I discovered that the door closed in flight shutting off the camera...
I ended up putting in a door retainer to keep this from happening.
I ultimately got better results out of the FlyCamOne2 because I was prone to use it more often.