High Gravity Partial-Mash Partial-Boil Brewing

I was trying to figure out if I could use one of my setups to brew Barleywine / Imperial Stout / Quad styles and was wondering if this would work. I can brew 5 gallon batches with a 12qt brew kettle. I was thinking that trying to use one wort in my 12qt pot would be practically unmanageable. Would this methodology work?

1. Make a 2.5gal wort with hops. I can partial mash ~6lbs in my 12qt brew kettle. I would go through the regular process with the grains but I wouldn't add any extract and I would add all of the hops that are required for a 5 gallon batch. Dump this is in the fermentor when finished.

2. Make a second 2.5gal wort, but this time just with the LME. Since i wouldn't be adding any hops to this, the boil time could be significantly less (15 min?) since all I was basically doing would be sanitizing the LME

3. Top off my fermentor with the second wort to reach a full 5 gallon.

I figure that this method would allow me to get much better hop utilization, much better control over OG (I could take a reading of the first wort and adjust my second wort recipe to hit my target) and would significantly cut the time of brewing since I would only have to run 1 boil for a full 60 minutes. Does this sound feasible?

Look up DMS and boilng wort. I think DME has DMS that you want to boil off.

Why not partial mash, add your LME and then your hop additions all in the kettle, put that in primary and then fill the primary with cold water until you reach five gallons? This will lower the temp. of the wort faster so you can pitch your yeast quicker.