I'm not surprised the fractal works, but with low gain. They are designed for wide bandwidth in a compact space. Stacked fractals might give enough of a boost, but there is also the factor of preventing side radiation from other sky sources from getting in the mix. That's where the reflector is very important.
The other alternative is a compact 4 element yagi. In a finished product, it could be something that "flips" out, uncovering the solar panel. In fact, there could be one on either end of the case serving as protective covers for the solar panel when not in use. That gives an immediate 3dB gain increase over one yagi.
I've also made an inquiry for a 4 element patch custom for L-band, just for testing. Another possibility for using as "flip" or "slide" out covers containing antennas.