BAC 65 too large for double Faber LP85s?

I bought a BAC 65 (w/bungees) on the recommendation of a tech instructor when I was just starting to dive doubles. I dive a dry suit, am cavern rated (most of my diving), working on adv. nitrox/deco and will be doing intro to cave soon.

When I bought the BAC 65, my plan was to double my 2 Faber LP108s, but wound up buying a used set of doubled Faber LP95s. I found these very heavy on land, especially getting out of the water, and also very head heavy in trim (with the BAC 65). I have since split the 95s into singles where they trim out great and are lighter than the 108s.

While I still plan to eventually double the 108s (when I need that much gas), I now use double Faber LP85s (7" diameter tanks vs. 8" for 95s & 108s) with the BAC 65. The trim is much better and I can keep a horizontal "cave posture" quite easily once established, but if I have to change positions, such as going head down in a descent, my head wants to keep going down and returning to a stable or horizontal is a struggle. This can be quite disconcerting when exiting a cavern/cave with any kind of flow pushing you while you are trying to vent the wing and drysuit to keep from shooting to the surface. I have none of these problems with a single tank (with a donut - 360 wing).

While I attributed these problems at first to getting used to doubles, I now have over a dozen doubles dives and beginning to suspect that the wing may be contributing to my instability. The horseshoe BAC 65 seems to be relatively narrow at the shoulders and much wider at the hips. I suspect that in the head down position, any gas in the wing goes to the lower and wider part of the wing where it may get trapped by wrapping around the narrower profile of the double LP85s. The left low dump will also only vent that side of the wing.

My questions are:

Is this wing (BAC 65) too big for double Faber LP85s? Is it better suited for larger doubles, such as 104s and 108s?

Can the bungees be used to correct some of these problems? I am playing with this now.

Would a donut doubles wing, like the Hollis C 45 (or Halcyon Evolve or Oxycheq Vertex), be a much better match for double Faber 85s? I think this may be where I am headed.

Thanks

I'm just past getting this sorted out--doubles can be quite a bit more head heavy than you might think, causing any number of interesting problems. It sounds like the shape of the wing might be contributing to that. You might want to try a tail weight, maybe 3 lb, and see if that helps. I used a pair of Faber 85s in a course last fall and had plenty of lift with my 40 lb Evolve--a Hollis C45 should be more than enough.