I have tried pre-plumped raisins in the bread pudding, I have tried macerated pre-plumped raisins.
I didn't get a load of flavor out of them, and found that when the pudding is cooked for say 45 mins they do it on their own. Now a rum raisin sauce is totally awesome and the standard faire on a Cajun bread pudding. See I sometimes forget that what I have grown bored with and reached out for new flavors others have yet to enjoy.
I do like the coconut milk and maple idea. I just like maple anyway .... why? Well I know about vanilla, but as a child my Mom only knew vanilla, there is no maple syrup in the south except Log Cabin. Boy when I had my first real maple I went nuts! Now I keep more maple extract than vanilla, and the reefer has 3 each 1/2 gallon jugs of real syrup, Grade B, Grade A fancy or light, and Grade A Amber. Did I mention I went nuts over maple....LOL
And speaking of nuts, I have put chopped pecans in bread pudding also, they usually cook almost tender.
But now I am rambling. I did copy your recipe and definitely plan on trying it!