For aerial photography flying “smoothly” like a brick isn’t much of an issue IMO. Camera, gimbal, VTX, extra battery add weight and affect handling.
No Phantom will ever handle like a 250 quad racer but as long as it manages smooth flight with a camera setup, what else does someone need/want? But on heavily loaded bird you will surely need more than stock 8” props.
This will likely kickstart a ton of replies about junk quality and poor hub threading but I buy cheap eBay props. But I do use a balancer (don’t sand, cut or file - use Scotch tape or similar for weight).
As mentioned earlier and before hacking up the shell to stuff more battery inside, try mounting single external mount off the rear and notch the battery door (which you gotta dow anyway for external dual batteries) for the parallel wiring dongle. Run stock internal battery and a single external rear mounted battery pack.
This arrangement not only helps counter balance the camera/gimbal but doesn’t block as much prop wash air flow under the blades as dual external batteries can do.
Loaded with dual battery packs, cam, gimbal, VTX, I set my timer for 14 min and still never see LV (low voltage) warning before landing.
OMT - with a single rear battery tray I was able to only slightly notch my cheapo Phantom backpack foam to accommodate my bird with the rear tray installed. Otherwise it was gonna require hacking a lot of the molded/formed foam to fit Phantom into the backpack foam with battery trays on either side. So there’s that too…