Dude, have you gone back and read my old theological post yet?

As to these points:
"I do see a problem with making doctrine without scripture but you can't avoid it. Necrophilia is not mentioned in the bible but can we agree that it's sinful?"

You must avoid doctrine without Scripture in my opinion. Sure there are some things not directly covered in Scripture, but the general principles that establish any doctrine must come from Scripture.
No I can't automatically say that Necrophilia is sinful. What if a guy's wife dies suddenly and he decides to hope on for one last farewell.... is that sinful? Sorry to be crude but I hope you get my point.
I don't think Necrophilia compares with masturbation. Most psychologists would agree that Necrophilia is an unhealthy obsession that is a problem for a small handful of individuals. Masturbation on the other hand would be almost universal and enjoyed by people who are quite emotionally/socially healthy in all other respects.
I'm sorry but I can only call something sinful when it clearly violates a Scriptural teaching.

You keep talking about needing a common definition for lust... but why?. Lust is not the question here.
The question is... what does Scripture teach regarding sexual purity that can be applied to the issue of masturbation?
Again I direct you to my study and ask for your comments.

Guilt vs Conviction.... I'm in full agreement with you on those points.
I think the moralizers and Satan are on the same team (hehe).

I agree with the inevitability of falling and our dependence on the mercy of God. It's the "oh well I can't really do anything about this" attitude that I think is a mockery. You say, "no matter how hard we try"... this is not an "oh well" attitude. But to say... "Masturbation is wrong, we shouldn't do it, but I will fail and when I do God will forgive me"... I just think that is too presumptuous. AND its basically agreeing with me that this is a problem that for the majority can't be overcome and its trying to make some kind of justification for it out of God's mercy, rather than saying... as I am suggesting... maybe God is not asking us what we think He's asking.

"Can't be overcome / not meant to be overcome." Oh dear dear! I can't overcome my gambling addiction, presumably then I'm not meant to and I should go and lose the wife and kids in a poker game?"
A gambling addiction does not qualify as a "can't be overcome" scenario.
Gambling addictions can be overcome. Any addiction can be overcome (even a masturbation addiction can be overcome)... doesn't make gambling or drinking or masturbation wrong of themselves per se.
Someone can play the "can't" card way too early in the "can I overcome this?" struggle. But when it comes to our sex drive I think the "can't" word comes pretty close. Paul teaches this in 1 Cor 7:9 "If they can't control themselves then they should marry".

Very obviously marriage is the ideal provision for sex drive.
But what if it don't work for you, because... well ... say... your a BL?

"relax, forget it until it happens" LOL. Really, for some of us its a daily battle... when is the time to relax?

I really don't believe that sex drive should be overcome anymore than hunger for food should be.
It needs to be mastered and self-controlled with the power of the Holy Spirit. And however we deal with it we must do so in faith, not in a "opps here I go again, thanks for your mercy God" fashion.

Blessings
Cat.