I don't think the risk posed by putting a diver, however well trained, into 900fsw is worth a body.
Absolutely quite agree hence the small lightweight ROV suggestion and besides as Akimbo states you need to know where it is first.
Very few things are worth putting a diver into that much danger for.
You need to say that on the rebreather forum.
You might just think that, I couldn't possibly comment LOL)