Things to take into consideration when brewing a higher gravity beer.

I'm going to be brewing my first Stout and want it to be a bit higher gravity. I have only done 4 all grain batches and it's been about 6 months since my last brew day so I'm a bit rusty. I usually go with like 12 lbs of base malt and then like like 2-3 lbs of specialty or whatever. What are some of the things I need to consider if I'm going from 12 lbs up to 15 or 16 lbs of base? How many pounds is too many pounds? I just want to get trashed in the middle of the cold MN winter. Thanks for any help or constructive criticism you can offer. Here's the current recipe before going up in base.

6.0 lbs Maris Otter
6.0 lbs 2 Row
1.5 lbs Crystal 60L
1.5 lbs Midnight Wheat
0.5 lbs Coffee Malt
0.5 lbs Pale Chocolate
0.5 lbs British Chocolate


Additions
1.0 oz Nugget @ 60 mins
1.0 tsp Irish Moss @15 mins
1.0 lbs Lactose @ 10 mins
1.0 oz Mt. Ranier @ 5 mins
1.0 oz Mt. Ranier @ flameout
2.0 oz Ground Coffee @ flameout

Mash @ 153
Boil Time 60 mins
Boil Volume 6.25
1.33 qt/lbs

Primary - 2 weeks @ 65
Secondary - 6 weeks @ 65 *add 3oz of Cold Brewed coffee at time of bottling

If your goal is just to create alcohal add some flaked rice, or flaked corn (corn will add a very small amount of flavor)... not sure why you would want to if it tastes good as it is.

Also worth considering:

The additional alcohol, if from base malt, could throw off the balance of the beer, and turn out nothing like the original stout.

I'd guess that rice/corn wouldn't do that, but you might as well just toss in a pound or six of dextrose and call it a day.