Are you talking about oddjob.bsp?
As long as your map has more than one path from base to base, it'll be better than most of the ones out there.
I think the reason those small 1-way maps are popular is because they don't require much skill -- people can just sit and spray in one spot and the other team HAS to go through it at some point.
How are you planning on doing the trees? Most trees end up looking pretty goofy in Q2 -- like pyramids or lollipops. You might consider doing something else that works better with the q2 format.