Like it or not, pipkin, if the technique you describe works your opponents are playing well. They have seen the possibilities of the new(ish) alliance feature; they have recognised the dominant importance of SH sieges in CvC; and they have organised themselves well so that the game's matching criteria work in their favour not against them.
Rather than indulging a sense of grievance you might profit from their example.
One thing you might do is organise yourselves in a similar manner. If your highest influence players: leave the clan; form a clan of their own; and ally, you will be in much the same position. Your draws in the future will be against lower influence clans and your ability effectively to conduct level 4 SH sieges will put you in a very strong position.
Another possibility is to look about and see whether diplomacy might secure you an alliance with a clan strong enough to: aid your siege defences; and to assist you in developing your SH/Tower of Odin so as to have a chance to match opponents such as the clan you currently face. Powerful clans welcome the chance to participate in as many SH sieges as possible. My own clan secured help in developing our SH to level 4 and getting the Tower of Odin built in exchange for ceding the right to conduct one SH siege each week outside the CvC period. If you are in a position to provide the precious dust needed for expansion and to run sieges my guess is that would be a good bargaining chip.
If studying your present contest appeals to you, it strikes me that you will need to watch exactly how your opponents and their ally manage their SH siege defences. They need to balance the troops contributed by the ally and those contributed by your opponent clan with a lot of care. It would be no good for the ally to put in the vast majority of the troops because your opponents only score points for the Jottun troops they kill themselves. Judging the kills required to beat your score (assuming you to be deft enough to avoid the attentions of the ally during your own siege) and knowing how many troops will achieve that target strikes me as difficult although I suppose experience would help.
I would be interested to learn whether the technique works in practice, particularly should you manage any effective scouting.