you might want to consider a 45 wing if one day double tanks might be in your futur.
they are decent for singles and will have the capacity to grow with you. Of course you would have to pick doubles that a 45 can handle like steel 100 would probably be the max depending on your other gear.
I do not agree.
Singles wing and doubles wings are shaped differently.
To handicap ones self with a "too big", "too wide" doubles wing when diving singles is not money well spent or money saved. Why negate the advantages of a BP&W in the hope that you MIGHT have the right wing for doubles, if you ever proceed to doubles.
The transition to doubles is not cheap. You need:
A couple sets of doubles, tanks, bands and manifold 2 x $900
A Dry suit and undies $2000
A few sets of regulators 3 x $600
Training $2500 ???
Not to mention deco bottles and rigging, spools and reels, and lift bags and smb's and and and and.
Trying to save the cost of a ~$300 doubles wing is just not significant in the over all scheme of things.
In addition, without knowing what exposure suit and tanks will be used for doubles it's really not possible to know what wing will be appropriate. Very few divers end up using the same exposure suit for ~45 minute single tank dives vs 120+ minute dives on doubles.
Tobin