My suggestions are much more about riding than equipment. Assuming the course is flat, weight isn't very important. Aerodynamics definitely are. Reducing the frontal area of your body with position (not suggesting you instantly loose 50 lbs) will yield the single greatest improvement. Since you can't have aero bars, you can lower your position by riding with your forearms on the top of the bars. It takes some getting used to but will give you a very similiar position as aero bars (in terms of height). You see the pros doing this in breakaways on the road.
Recent windtunnel tests (off topic?:-) show that helmets are one of the biggest offenders. If you're older (likely) your neck isn't as flexible as it once was. Riding with your torso down and neck craned up so you can see will be difficult. However, if you ride with an approved helmet and keep looking down, the back fins of the helmet are big offenders. Tape off the vents in the helmet at the minimum.
Removing the one chainring and FD are a common old school method. However, if the course is rough/bumpy, you can loose your chain without the FD. David Millar is familiar with this issue about a year ago.
(can't climb or sprint but could TT)