Rain gear.

[G-Rex]

I love my Aerostich, and will highly recommend it. It is not cheap though, and your list of advantages and disadvantages is pretty much spot on.

There are cheaper alternatives in textile suits obviously. I've seen/read good things about alot of them. Tourmaster actually makes a pretty nice textile suit from what I've seen believe it or not, so you might look into that. The only bad thing with that suit is that it is vented, and comes with two liners to make it wind and waterproof. Good in that the hot weather won't be as much of a problem, bad in that it defeats the purpose when you would have to stop and put the liner in if it starts raining.

Just have to weight which abilities are more important to you.