Plenty of people I know in Wharton did not take Calc BC in high school. You should take it if it's available, but if it's not it will not be held against you. I would give the same advice to anyone applying to any school of Penn as well.
You don't have to be that dedicated to math to do well in Wharton. Plenty of people start out in Math 104. You need to be proficient and comfortable with calculus from what I understand, but no further knowledge is really required. There seems to be a lot of talk about optimization problems using of Lagrange multipliers in BPUB 250, but those are pretty basic methods which are developed in multivariable calculus.
While there are some people in Wharton who really enjoy math and choose to complete further studies in it, most students seem to stop after Math 104, which is the first semester of calculus here. So if you did well on the Calc AB test and got into Wharton, you would just have to take that one math class.
As for subject tests, I think Math II is recommended.