Big splits vs. 4-2-5

I agree with coach Easton and coach Mountjoy, big splits essentially put the offensive linemen on an island as well, making it much more difficult to double team. I would go after this team with as much speed as I could since there is more space to work with defensively and you are likely to see predominantly one on one blocks.
Other than blitzing you may consider putting your faster linemen inside and some of your linebackers at DE to get more speed on the field, if you have enough players to do it without a significant dropoff in talent or execution.