Depends on what you're after. If the goal in a low mash temp is to attenuate well (with a low FG) and have,for example, what the Belgians call a 'digestible' beer , then it seems counterproductive to drive the FG back up with unfermentables. I'm not saying it can't ever have a place in beer, but I'd rather control body with mash temp most times. YMMV.
8oz of Carapils in a 5.5 gallon batch will increase FG by 0.001 gravity point at a low mash temp without increasing subjective sweetness while adding more body than the same beer mashed higher that finishes at the same gravity and sweeter.
Like you said. It all depends on what you want to achieve. Carapils can achieve things that can't be duplicated by the same grist without Carapils at a higher mash temp.
I brewed an all Pilsner base malt IPA with carapils to bump up the body inspired by this thread yesterday.
But I stick by my original remarks... I don't "think" you need the carapils in this recipe. Not am absolute, just a suggestion. I think that there are too many IPAs out there with too much perceived body. And there is no suggested mash temp. So in reality, in this recipe, I'm not sure what the carapils would be for. But maybe it's exactly what the OP wants.
First time I used cara pils in an IPA recipe was 10 years ago in a Russian River Pliny cone and that turned out pretty good, but Ive not used it in an IPA recipoe since and they've turned out purdy good, too.