I think there could be a market for this amongst the safety concious who would prefer a twin for regular overwater / montain flying.
I have a modest 70hrs on piston twins, I tend to agree with IO540 in supposing that theoretically you have double the chance of engine failure with a twin. If that is the case then a single would probably be preferred as most normally aspirated twins would struggle to hold 4,000' AMSL on one engine, probably more like 3,500; which is less than the MSA over just the hills of the UK. Add turbocharging and you're probably well to the right of relatively 'affordable' compared to a decent high performance single, even then don't expect much above 8,000'.
However, I wonder if you really do have double the chance of failure in a twin. I suspect that a significant number of engine problems/failures are due to maintenance, misuse, mismanagement or missing fuel. Suggesting that if one goes, the other may well follow soon suggesting that to most practical purposes the extra expense of a twin really probably is about peace of mind rather than any significant strides in terms of safety.