Electronic & Hydraulic Shifting (Di2, Ui2, customisations)

i am so fed up of chain slap and subsequent chain drops on 12sp ultegra (r8100)... maybe every 1 in 10 potholes if i am in the 11t the chain slaps and works its way off the bottom of the crankset. crankset is now super scratched up. completely crap - never had this issue with r8070

i am now convinced the issue is with the actual cage tension itself. the b screw tension is correct, the chain length is correct, the limit screws are perfect (haven't ever dropped chain during shifting), the hub has very very little drag.....

see a video which demonstrates the problem - https://imgur.com/gyyTTCd

i opened up the cage and it seems the spring can't be tensioned upwards/adjusted unlike previous generations which is shit. has anyone had any luck with an oem cage? i dont want to buy a ceramic speed one because i am not a tool but would be happy to investigate other options

other strategies I could employ before binning it and going to sram:

• change to a 30t cassette (vs the 34t i have). running the 52/36 at the front so this would bring the chain length down a bit and therefore increase the cage tension... it isn't a deal breaker losing the granny 34t but i do actually use it on some local climbs (whitedown lane, barhatch)
  
• try with a different RD... maybe mine is just shit?
  
• take another link out of the chain to make it really really short. below image shows the chain with a hypothetical link removed (see fold in chain on cassette) and shifted into 34:52 (i.e. BIG:BIG ultimate cross-chain)
  
  

which strategies would you choose and in which order?