I think the way you are proposing is the most cost effective way. Especially if you gain an CBIR via an IMC rating and then do a single engine CPL at the end.
I know of two people who did it the way you propose and they both got jobs flying 737's on completion. One paid 41 grand from start to finish. As for the other I'm not sure but I suspect the price would be similar.
If you do the IR last you do have the advantage of tackling what most people would regard as the most difficult (and expensive) flight test last.