If you don't mind using mods, MechJeb's landing module is essential for aerocapture/braking as it gives you a predicted AP depending on where you put your PE in the planet's atmosphere. You may need more than one orbit for greater precision. Also, if we eventually get G-loading/heat sensors for crew survivability, it may be better to do it over a series of orbits instead of one big aerocapture really low down in the atmosphere to get it done in one orbit.