Big beer in a small space

My last brew was a bit of an experiment. I had just finished reading Brewing with Wheat, and was gung-ho to do something using a significant amount of wheat. Summer is also nearly here, and the desire to drink big beers will be fading with the arrival of warmer temperatures.
One of the beer styles described in Brewing with Wheat is called a wheat wine, something I had never heard of before, but the gist is that like a barleywine, a wheat wine is a wheat beer (using at least 50% wheat), with high ABV and equally high bittering. Styles vary from there.
I decided to fashion a beer that is strong, uses a large portion of wheat (but not 50%), and with moderate bittering. My hope was to bring in something close to an English style barleywine, but with added character from the wheat.
I also did something new this batch. My friend offered to let me use his 10 gallon cooler mash/lauter tun for this batch,and I filled it to capacity. My grain to water ratio was about 1.2, and it was so full that I was unable to stir during the first mash, however I did stir as I was adding the water for the second sparge.
I ended up with a rather low efficiency, around 63%. Not ideal at all, which brought my OG in at around 1.080, rather than 1.1+ which I was shooting for. Oh well. Brew and learn.
I also used whole leaf Challenger hops in this batch, and I have to say that I really do love using whole leaf hops. They are very visually appealing, and make for a much cleaner transfer into the fermenter.
I used S-04 in this batch, and pitched the two packets of yeast that I prepped, having planned on needing them both for the expected huge OG. Fermentation took off within hours, and I had to hook up a blowoff tube before i hit 24 hours.
I’m planning to age this beer over the summer, and to use oak chips in the secondary. I’m looking forward to this in the fall, when cooler weather comes again.
Several questions arose from this session:
Does the grain to water ratio effect efficiency in such a way that you can reach a point where more grain actually delivers a lower OG? If so, where is that ratio? I know that I’ve seen ratios as low as .75:1, and as high as 2:1. For a mash tun that requires that you open it very little to prevent heat loss, and a lower ratio requires more stirring, is a higher ratio recommended? And with low mash ratios, is a longer mash needed to gain efficiency?

It is my understanding that you have to go REALLY low in water-to-grain ratio to lose efficiency. Like, well below the 1qt:1lb ratio.
I don’t do any stirring during my mash – I let it sit, and I often get over 80% efficiency. I also use water to grain ratios that are somewhere around 1.5qt:1lb (when I have room), so I’m not sure you need to factor stirring space in on the equation.
I do find that the thicker my mash is, the harder time I have getting my beer to be clear at the end, but I can’t tell you, on a science level, why that would be.
Finally – my normal solution for making big beers and fitting it into my mash tun is to make smaller batches. I normally make 3 gal. batches of my big stuff vs. 5 gal of “normal gravity” beers. That way I drink them at about the same rate, too.
great advice erik. I’m also going to try returning to my earlier methods or pseudo-fly sparging to see if that helps at all.