I do know the answer.
One Infantry is 0 tons, and the smallest unit Aurora can make. One Headquarters component is variable in command rating (user set), 10 tons, and INF-mountable.
One junior officer, freshly graduated, is Command 10, 0+10 tons, cost (with starting tech) 0.00001, Annual Maint 0.0005.
An Army (unit) of One, as the saying goes.