Coconut Rum Porter Recipe Help

Trying to get some opinions on a coconut rum porter recipe. I'm not looking to use anything like malibu's coconut rum but rather using actual toasted coconut and aged rum. My friend found a rum which is a 12 year old bourbon barrel aged blended rum, it's sweet and delicious and he wants to make a beer with it. After looking at recipes for a vanilla porter, bourbon barrel porter, and KBS clone that I've done plus a maui coconut porter clone, we've come up with the following recipe.

5.5 gallon all grain batch
OG 1.060-1.070 (maybe 1.068?)
IBU somewhere in the low to mid 30s?
Mash 155 for 60-90min
Boil for 60-90min

10lbs Maris Otter
0.5lb Black Malt
0.5lb Pale Chocolate Malt
0.5lb Dark Chocolate Malt
0.5lb Dark Crystal
0.5lb Oats (to help with head retention due to coconut oils)

Hops
1.5oz Goldings 60min
1.0oz Willamette 30min
0.5oz Goldings 15min

Yeast either 1056 or a London ale yeast

28oz of coconut toasted at 325 for 20-25 minutes in secondary for 14 days
16oz of rum in secondary

As you can see the recipe is a little loose but I think it's a pretty good start. The only software I have for beer recipes is an app on my phone so it's not the greatest. We've never worked with coconut before so I'm not sure about amounts and toasting it. The good thing about the coconut and rum is that if it ends up being a little too much we can age the beer and it should mellow out.

Also not sure if we should put the rum on any kind of oak before tossing it in.

Any suggestions would be much appreciated

If anything I'd say swap the oats for flaked wheat if the only reason you're adding it is to help with head retention. Oats will add more body than retention to your beer, whereas the flaked wheat will add retention with less body. Hope this helps!

ah, cool, good to know. I've used oats before to add body but haven't used wheat. Maybe keep the oats for added body since it's a porter but also add wheat as well.

Thanks for the tip

Think we might go with the wyeast 1318. I've seen a few other recipes similar to ours that call for this yeast, it's supposed to finish slightly sweet with a softly balanced palate. Sounds like should compliment the the coconut/chocolate/rum.

Correct me if I am wrong, but the recipe looks more like a stout than a porter. I thought porter would have less of a roasted character than that much black malt and more of a malty sweet character. Just clarifying though

I was wondering about that myself. The recipes we were looking at were mainly porters but there was a stout or two we had looked at. We were thinking that adding some of the black malt would offset the sweetness of the coconut and the rum. All just guesses though.

Coconut is oily, which may affect head retention. I'd add some wheat for that reason alone.

I haven't used wheat much. Think 0.5lb would be good enough for a 5g batch?

How did this turn out with 16oz of rum?