On my 95, I could reach the drain tube from under the passenger seat. You just want to make sure that the tube didn't get pinched. Don't pull out the tube.

 

Jim, Thanks for the schematic that helps explain a lot for trying to clean the drain tube. Do you have the parts list that goes with the schematic? I am curious what item 30 might be. It looks like it could just be a clamp for the hose, but I can't tell.

 

I think #30 is a hose clamp.
www dot hondaautomotiveparts dot com
click PARTS
put in your car's information
category is SLIDING ROOF or something like that.