To the previous poster - read the original post, he's already pre-conditioning his grain
To the original poster - I think folks here are on to something in that you're probably not using enough water to rinse your grain. It sounds like your boil volume is limited by your equipment but maybe you could consider doing two boils - either at the same time in two pots or one after the other using one pot. To figure out your water needs...
1. Start with your batch volume (let's assume 5 gallons to keep the math simple)
2. Add your boil-off volume (you say you lose 1/2 gallon so let's use 1 gallon (two boils)) so your pre-boil volume is 5 + 1 = 6 gallons.
3. Ideally, your runoffs are equal volumes. Since you want to end up with 6 gallons pre-boil volume, your sparge should use 3 gallons
4. To also get 3 gallons from your initial runoff, you need to account for grain absorption and deadspace. (let's use .1 gallons per pound for grain absorption and 1 quart for deadspace). If you're using 10 pounds of grain, it's going to absorb 1 gallon. Add that to the quart that's lost to deadspace and your total water needed for the intial runoff is 3 gallons (runoff) + 1 gallon (absorption) + 1 quart (deadspace) = 4.25 gallons. You can use the total amount as your strike volume as it's within the acceptable range for water to grain ratio (4.25 gallons = 17 quarts and that, divided by 10 pounds of grain, gives you 1.7qts/lb).
So, you can heat 17 quarts, dump it in your cooler, and mash in the grain. Mash for an hour, and then runoff the first runnings. Split the runnings between the two pots (or one pot and one storage vessel). Then heat 3 gallons of sparge water, add it to the cooler, stir, vorlauf, and runoff. Again, split the runoff between your two vessels and, once you're done, you should have two containers each holding about 3 gallons of roughly equal gravity wort. Proceed as usual.