I’ve tried this. The first time I did it, I used 2T bourbon and subbed it for an equal volume of the cream so the pie filling wouldn’t be too runny. I have in my notes that the acidity of the bourbon was enough to curdle the dairy, and that 2T was too much, flavorwise.
For my next trial (which may be tomorrow, yippee for Rose’s pecan pie), I’m going to scale back the bourbon to just 1 tsp and add it with the vanilla, off the heat. But I won’t know about the success of that until after Thanksgiving.
The curdling could be due to my use of a pasteurized (i.e., not an ultra-pasteurized), heavy jersey cream- it seems to love to curdle at the slightest provocation. It may need a pinch of baking soda to work, or it may be fine with just the lowered quantity of bourbon.
The time I made the pecan pie as written and paired it with the bourbon whipped cream (both Pie/Pastry Bible) the whisper of bourbon was sublime. Hence my desire to experiment with adding it to the filling.
Good luck, please let us know how it turns out.