I can certainly empathise with your conundrum. I have an H520 which I had great aspirations for at the time of purchase, not the least of which was the ability to hot swap across different payloads. Then I ran into the problem of delay on delay, and in some cases downright BS from Yuneec (China) around supply and delivery of the CGOET gimbal, to the point where I decided this degree of hassle wasn't what I wanted when trying to set up a small business. There were enough difficulties around flying reg's in my home province where close to 70% of the area is tied up in conservation land/national parks, without trying to work with a less than ideal aircraft configuration as well.
After trying to sell the H520 with extra batteries and spares, and getting absolutely zero interest, my solution has been to utilise what I have; adding a Parrot multispectrum system that can be fitted to the H520 with aftermarket brackets (the Parrot unit can be utilised to fit pretty much any multirotor or fixed wing UAV) and fly the H520 into the ground - figuratively.
My solution may not fit around your ideas/options, but months of agonising over "sell, don't sell" and more than a few feelings of "woe is me" for being (self) suckered into buying what is essentially a very good aircraft, unfortunately put out by a company whose concepts of aftermarket support seems to be non-existent, seems to chime in with your thoughts as well. Hopefully you can draw some solace from knowing you are not the only one to experience such a problem about what to do with a seemingly "flightless" UAV.
Maybe a bit of lateral thinking might offer up some solutions.
Safe and happy flying



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