I've always used the juice, rather than the gel - the gel has additives that may not react the way you want.
I count it as part of my water - either mix it into the water and dissolve my lye in the solution, or short my water by X amount, dissolve the lye in the reduced water, and add X amount of aloe at very light trace.
I'd probably keep it at about 1/3 the recommended water amount.
questions on the above.
1) how do you get aloe vera juice? peel and blend from the aloe vera or using the bottled drinks (contains sugar)?
2) any difference when adding the aloe vera juice with water then add lye into this mixture, when compared to adding the aloe vera juice at light trace (reduced water during lye mixture).