I agree, this is a challenging quest and I've been looking for a long time. last night I rode in my trisuit with a yellow jersey over the top. try the spandex - it's OK if you're on the bike. I find walking around in it a little disconcerting so I sometimes carry shorts if I expect to take long breaks among non-cyclists. if you're gonna stay on the bike for a couple hours just wear the spandex - it actually feels great.

I came close to getting good over shorts but they just don't behave properly on my thigh above the knee with each pedal stroke. REI has a bunch of stuff you might go try on - but they are expensive.