MMP uses characteristics for model-mix planning, so it is pointless to use MMP without product characteristics. Therefore, your iPPE product headers should support characteristics. To support characteristics, you have to use iPPE access nodes and structure nodes instead of iPPE Assemblies, at least at the very first level of product (if you are not going to use MMP for other product levels, such as for cabins or engines). You probably can use iPPE Assemblies (also phantom ones) at the second level, but there will be restrictions for backflush of phantom assemblies used several times in the same product: for iPPE Assemblies, they all will be backflushed together during the very first backflush.
Also, I would suggest to stay away from APO-based IS-Automotive in general, because it is a dead-end solution in "maintenance mode": there won't be any significant R&D investments to it in the foreseeable future. Besides, you will have issues with limited SAP Support resources for this solution (which is not rock-solid stable btw.). So, you should have extremely serious reasons to use APO-based IS-Automotive, but if you don't use VC, then half of the reasons probably don't exist for you.
