Andrew,

You still want your cake and eat it too.  You want a high priest in heaven (which we have), having entered heaven itself to present His blood as the cleasning for sins (which He did), while denying that this priest suffered (in his priestly capacity) as the sacrificial victim ‘outside the camp.’  Do you really think it coherent to isolate His heavenly priestly ministry from the earthly offering up of Himself as sacral victim on calvary?  When He offered up His life on the cross as the victim (laying down his life, as John’s gospel puts it), you’re saying, he was NOT acting in his priestly office as the Messiah of Ps.110?  Sorry, man, this is just too artificial and contrived.  He obviously was functioning in his preistly capacities on earth, just as he exercised messianic authority prior to his ascension and ‘coronation’.

You rightly note that priests do not offer up themselves in the Most Holy Place.  That is precisely the glory of His priesthood - He enters the heavenly tabernacle through His own blood!  Blood shed not in isolation of his priestly ministry, but as part and parcel of it (just as slaying the animal was part and parcel of the priestly service in the Levitical economy).  It is the basis of His continuing intercessory ministry.  How can you deny this?  (Perhaps because your prior eschatological commitments forbid you from seeing it otherwise?)   

"In the terms of the analogy it is not his death which is once and for all but the subsequent offering of his blood in the heavenly sanctuary."

As in Leviticus, this is all of a piece.  Read again Leviticus 1:2ff.  The offering up of the animal to the Lord INCLUDES the slaughter of that animal.  And so with Abraham’s offering up of Isaac.

Regarding this, you write "Abraham is told to take his son and ‘offer him… as a burnt offering’: it is the burning of the victim that constitutes the offering, not the killing". 

But once again you are carving up what was seen as a single ‘complex’ of events into artificial compartments (‘offering’ Isaac refers only to the burning of the corpse, not the plunging of the blade into his chest?  This is absurd).

So Jesus offered up himself once and for all on the cross, and entered the heavenlies, cleansing for sin once and for all. This is not either/or, as you’re suggesting.  Hence, to repeat myself, otherwise he "would have had to suffer many times since the creation of the world," 9:26.

And again, you fail to explain the significance of the passive verb, where in Jesus is not acting as priest, speaking precisely, but being acted upon as victim, as in 9:28 and elsewhere.  Your continued insistence that it refers to the priestly task of offering blood in the Most Holy Place is just skirting the issue, and apparently missing the point.