TBH if you're looking to make last easier to manage the map itself is solid at its core, the reason it's so hard to push is the amount of space afforded to the defending team to kite ubers (distance).
The last itself would be easier to push out of and push into if the point itself were much thinner.
This could be effected by: moving the right side door (assuming we're looking at second from last) to the left scrunching up the map that way so the last point is smaller and the lobby area easier to navigate with less distance to cover - thus easier to push last and easier to push out of last.
I don't have any mapping skills, but the outside edge of the shack would be a good starting point. Just cut off everything to the right of that shack and scoot the lobby door and the interior of the lobby over accordingly. Some space on the left could also be taken away inside the lobby and on last itself if you *really* wanted to go crazy.
That way when you push out the left most door and the right door are fairly close together and can be cleared quickly. While defending last the opposing team would not have tons of space to run away from an enemy team's uber.
Just a suggestion if you're really in the mood to toy around with things lol.