Well, I am not at the shop right now, so I don't know exactly (I mean, it IS Sunday). My recollection is that the min-humbuckers are not as long as the P-90s, so that might look a little weird. As for regular humbuckers, any of the repair folks in my shop could make it look decent, but it is just about impossible to make it look great. It will never disappear without refinishing the whole guitar in an opaque finish, which is FAR more expensive than it is worth. Just the refinish is going to run you $400-$600 dollars, and that is for a simple opaque, not a candy. Candy's are WAY more expensive. There are other shops in the country who specialize in refinishing work who are less expensive than us, but you would still need $100-$200 worth of woodworking.
You might want to check out the Gibson P-100's, or the Seymour Duncan Antiquity line humbucking P-90 style pickups. Seymour makes at least four different P-90 sized pickups. I would imagine that at least one of them would work better for you than what you have. And in the end, it may just be that you have to tell your wife, "Thank you so much for the thought, but this particular instrument doesn't work for me." Then use the money to get one that does work for you.
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"Cowards can never be moral."
M.K. Gandhi