Day 1 I would boil half the extract with half the hops, chill, and pitch. Day 2 I would boil the rest, chill, and rack onto the previous days now happily fermenting wort. Without doing a full boil you won't get the IBUs the beer needs to be Pliny. Doing a two step boil will also keep the color lighter and the flavor less melanoidin -y. You can also adjust the amount of water you use the second time around to get to the right volume in the fermenter.
The gravity numbers in that recipe look a bit off to me, there is enough extract/sugar to get you to ~1.100. You'll lose some to hop absorption, but I'd be surprised if it is 1/4. It is already slightly bigger than PtE as it is.