Your exploration area sounds very interesting, particularly since you know it is risky but you still feel a need to go there. I would love to know more so that I (we) can better understand the challenges you face…do you have any video or photos that you are able to share? Are you operating in fresh water or seawater? Is the wall a cliff or a crevasse and how much clearance do you have to operate? Is the route to the wall a zig-zag and/or is there a significant overhang or swim-through along the route that restricts manoeuvring…
If your greatest challenge is the tether then this may be difficult to solve. I avoid the risk of tether snags by carefully planning my entry/exit points and by routing Trident away from snags including by using Trident to drag the tether away from snags, accumulating free tether in a clear space of water near the target and then doubling back to the target from a safe direction.
This is not always possible due to current and surging but it is a general principle that I try to follow. I have also created a pool based obstacle course to help operators practice tether management and to provide them with experience getting tangled (and subsequently clearing snags and tangles remotely). You might also find this of benefit in your case since you are unable to dive to clear a snag, particularly if you can create a realistic set of obstacles based on the challenges you encounter.
The use of clump weights to submerge the tether and to hold it away from snags may also provide a benefit. This may require you to deploy Trident from a boat or kayak located offshore of the wall.
Oh and yes, I take great care to protect and maintain all of the equipment that I use and I also keep spares for everything. The guys at Sofar do not yet sell spares (except for the accessories like the controller, tether, reel and case) but I am hoping we will soon gain access to critical spare parts. I have replaced all of my motors and I have kept the old motors that still work as spares. I have also been able to partially refurbish some of my motors (there is a growing body of knowledge about motors thanks to posts by others here in the forum). The Trident community might come up with a solution to the spare parts challenge if required.
I hope these ideas help.