At 20w on a 10g, you actually have plenty of light to grow an abundance of plants. The w/g rule doesn't really apply to the small tanks. I have a link somewhere that explains this further. I'll see if I can't find it.

As for your filter, add a pre-filter over your intake. The best way to do it is get one of the AquaClear (AC20 should work just fine) filters and cut a slit in it almost to the bottom. Should fit perfectly on the intake. This will allow you to place plants right up to the intake and not have to worry about them.

For your flow, you mention you have a baffle in front of it already which is good. Another option would be to change your filter to a mini canister which will make use of a spray bar. Very good option here for planted tanks. I'm in the process of swapping mine out.