I have made a custom frame of the BlueROV2 Heavy.
Some upgrade is:
Height of the BlueROV2 Heavy is 308 mm instead of 254 mm,can have 3 aluminum tube under instead of 1 3".
Front center panel and Rear center panel is in two part not four part.
Heavy Thruster Guards is screwed to the back of the Side panel instead of use Heavy Guard Brackets.
The whole frame is made of 1/2” thick white HDPE.
All 6 lights get power from surface and not from battery,i use two Lithium-ion Battery (14.8V, 18Ah) sow 36 Ah,there will be enough to run the BlueROV2 Heavy for many hours.
I also have Foxeer Legend 3 4K Camera in the one of the 3 aluminum tube under (camera is in middle) will test it soon in the pool.