Multiple types of beer from one boil?

[Brewkowski]

I was debating doing a Partial Mash 10 gal batch with a 5 gal or so boil. I was planning on a lighter german ale like this:

8oz Honey Malt, MaltSpecial Roast, Flaked Wheat, Flaked Rice, Flaked Corn

2lb Two Row

3lb Wheat DME

3lb Light DME

2 oz of Tettnanger spread out to make about 40 IBU or so and a 4-7 SRM.

I haven't worked any of these numbers since I'm at work, but it's my general thought.

So my question, without having to do another batch boil, would it be possible to have some steeping grains or use a dark DME to add to this recipe with some additional hops (Fuggles) to make half of the batch a little bit different. I don't really have the time to do two full batches so I'm trying to go half ass and cut some corners, it's not right, and it's just a thought.
What if I put like a 1lb DME with 1gal on the stove while i boiled the rest and added some hops to it, then added it one half of the batch before fermenting? I know there are much worse things than drinking 10 gal of the same kind of beer, but I only brew like once every two-three months so I'd like to have a little something different for that time.
Is this just a completely bad idea?

 

[GilaMinumBeer]

I used to do this by steeping specialty grains on the side but calculating IBU's as if the sugars were in the boil.

Post boil, I'd split the batch and blend in the specialty concoction.

It worked but, the base grain character, hop character, and IBU ratio were still too similar for me to continue the practice.