| | Re: Overloading of gel
I mean, if each lane can hold 60 uL, add loading buffer to your 120 uL and load 3 neighboring lanes of the gel with equal amounts of your digest. Then, in your next step (I assume a gel purification?) pool the three lanes as soon as it is practical.
There are problems with both my suggestions: splitting the digest will make your next step a little more complicated with the re-pooling, and will take up more reagents as you have to do the first part of whatever you're trying to do 3 times. However, precipitating your DNA and trying to run it all in one lane can cause issues with gel migration; generally I see a decrease in effective resolution between sizes of fragments when the lane is overloaded (what would be nice bands can become smears).