Markbass Traveler 151 and NY151 are great and both weigh less than 40 lbs. I use their discontinued Club 15 and I love it. I'm a Markbass guy primarily but Mesa's stuff is always great too. Switching to a 15" should help for your needs as long as you get a good quality cab. I've tried all kinds of rigs and I always come back to 15" drivers, and usually I favor just one for some reason.
Another thing to consider is that many of the light weight cabs also use lighter and/or thinner plywood to build the cabs. That's part of what makes my 15 so light but I'll admit it does compromise the sound a bit. Seems like you might have thought of this. Your orange cab/lightweight driver idea might get you some of the best of both worlds but I'd try to talk to a cabinet expert first.
Another thing to consider is that many of the light weight cabs also use lighter and/or thinner plywood to build the cabs. That's part of what makes my 15 so light but I'll admit it does compromise the sound a bit. Seems like you might have thought of this. Your orange cab/lightweight driver idea might get you some of the best of both worlds but I'd try to talk to a cabinet expert first.

