Good work, I must say I like the idea for an extra base entrance, but I can imagine that people who like the map to be close to the original do not like it.
In the beginning UnderRedux was a great map, but as soon as people knew the sneaky roads it became a stalemate fest. Usually every base entrance is camped and the natural way of this map is GDI shelling the Nod base from the field, while it's hard / almost impossible for Nod to mobilize people as soon as the base entrance becomes free. Trust me, we tried on Under a week or so ago and it took hours...
On PUG's, where the coordination is likely better, I think I never saw Nod winning.
Why not:
Make the changes to the map you are making now
Save this as a map
And make another map with the same changes as mentioned above, but with an extra base entrance.
I like the river on Lakeside, maybe you can use something like this on the back of both bases to come with a whole new way of attacking / defending?