@ John
I think what you might be missing is the Soulo is a 4-season tent whose the outer rain fly comes down right to the ground. So even if your bag is pressing up against the inner tent, there is still a couple of inches of dead air space between the outer surface of your sleeping bag and the inside surface of the outer skin of the tent which in my experience mitigates the risk of condensation.
In most USA-designed, double-skinned tents, when your bag is pushed against the inner tent, what is on the other side is the cold, outside air since the outer rain fly does not come to the ground.
For winter camping, I use a somewhat different Hilleberg tent, the Akto. In my Akto I do not experience condensation at the foot or the head. The condensation appears around the door vent and inside the vestibule.
You might need to check is whether there is enough headroom in the Soulo. I have been using a Hilleberg Akto for years but recently switched to a NeoAir pad and now wish for a bit more headroom when changing clothes inside the tent in winter.
If you think you need more length and your tent has not been used outside, and you bought it direct from Hilleberg, exchange it for a Nallo 2.