Secondly the missus is incredibly concerned about flying in a single engine plane, which also means she's terrified about me doing it! Hence, I was wondering if there was a potential way round this, as that would make her feel better,...
The missus is misinformed. Flying a twin engine is more accident prone than flying a single engine. Unless you're doing long stretches over water (to the cottage in Sweden or something) or other inhospitable terrain, flying a single is a lot safer.
You could explain her that
a) an engine failure in flight on a properly pre-flighted and correctly maintained modern aircraft is a VERY RARE event, rarer than the missus and yourself having an accident driving to the airport
b) an single engine aircraft with an engine failure becomes a glider (albeit a heavy one)
c) the main accident causes are pilot error (such as flying VFR into IMC and mid-air near an airport, neither of which can be resolved by adding an engine) and you promise to do everything by the book, always, because you love her. This might imply that you won't be home for supper on some occasions.
As Backpacker pointed out:
- probability of an engine failure is about double in a twin than in a single
and also
- inexperienced pilots are much more likely to mishandle an engine failure in a twin than in a single
Second point is insurance : unless you own the plane and/or strike a good deal with an insurance company, they won't let you solo a twin with under 250 hours TT (of which 50 on your twin). And then we are talking a BE76 Duchess or a PA23 Aztec or some other twin that only makes sense as a trainer. For a proper Cessna 310, no insurance company will sensibly underwrite your soloing under 500 hours (even if you owned it they would ask for at least half of that).
As insurance is important in your particular case (not only do you want to protect the capital invested in your plane, you want to make sure to take care of the missus in the rare event that something does happen to you), the underwriting restrictions will dictate your line of action.
Third point is learning efficiency. It is a hell of a lot easier to operate a spam can (or a warrior, katana, cheetah, ...) than a Duchess. Even with proper ground preparation, it will still take you longer to properly fly a circuit and land a twin than to do the same with the spam can. No matter how good your instructor is, you would lose precious flying time with basic handling of the duchess.