There is no such thing as a Trappist IPA, or even a Trappist-style IPA.
Trappist yeasts are used in Belgian-inspired beers that aren't Trappist-like in style, including things like New Belgium Belgo, but please for the love of good beer don't describe something as Trappist-style when it's not. (I prefer Americans not even refer to beers that are distinctly American-styled like American IPAs as Belgium when they nudge them slightly toward that rather than actually making a Belgian-style beer or a riff on a style found in Belgium.)
That said... consider a grain and hop bill that seems like an English IPA or one of the less intense American IPAs, possibly subbing in some noble hops for some or all of the later additions, and pitch the Trappist yeast (I'd go with either Wyeast 3787, from Westmalle, or 1762, from Rochefort; the latter has a little bit less pronounced of a Trappist character but is still unmistakeably so) and then ferment a little warmer than you often do. Consider a sugar adjunct to boost attenuation.