It does sound like you're making it a bit harder than it needs to be. A ME/CPL course is an approved 28 hour course including at least 8 hours MEP flying as opposed to the 25 hour SE/CPL course with at least 5 hours complex single engine. As MJ says there's little or no benefit doing the bulk of a SE-IR before the CPL, other than being a little slicker on tracking and the limited panel work for the CPL - any competent school would make sure you are up to standard anyway!
It is of course entirely up to you how you do your training and you may well have a good reason, financially or otherwise, to do it this way round. But the established training routes are there for a reason, because they work...