Have you talked to her about you having a sexual partner outside of the marriage?
I'm not sure that should necessarily be ruled out.
Buncha stuff going on in your posts.
1. can you orgasm when you masturbate? not sure I know many men who don't wake up erect. There's a reason people refer to morning wood. You need to take care of that first thing ... and not 'deal with it' all day.
2. have you talked to her seriously about this possibly being a deal-breaker? is one or both of you prepared to end the marriage over this? if not, why not?
3. what alternatives to straight on intercourse is she willing to try?
I'd probably go the old red pajamas/blue pajamas route. The question isn't whether someone's going to wear pajamas but which ones they're going to wear.
If she doesn't want to have sex as often as you do, then she can choose to have more variety when she does have sex with you. She can choose what toys/oils/stimulants are used.
If you don't want to go outside the marriage to have sex, what are you going to do? porn and masturbation aren't a big deal, never have been. there is certainly more porn selection around, but it's been around for millenia. Porn is truly nothing to feel guilty about - unless the secrecy turns you on a bit.
What turns her on? work on that side of things more. Watch porn with her, women are extremely visual. Buy her books that might stimulate her - there's some hardcore stuff out there disguised as romance novels. Get all the fun lotions and potions and toys.
You have so many options. Talk with your wife (perhaps with the help of a counsellor or doctor at first) about what you are both going to do differently.
If either of you balks at talking about this - counselling is likely needed for reasons beyond just the sexual drive differences.