I'm sorry but I have no solution for this problem. This is one of those times when you just have to decide what is more important. Sponsor features or a customized layout and no features. Or if you wish to have everything, a paid account.
EDIT: I'm sorry but officially the layouts are as is. No way around it. You cannot alter in any way shape or form the ad css. If you try LJ disables your css sheet.
/* suspect CSS: trying to alter LiveJournal ad placement */
So sorry guys. Can't have it all.