Well, you already know about pushing shadows or pulling back highlights...and I'm assuming you shoot in RAW...
So other than multiple exposures and blending in post (which might not be ideal for some things), the simple solution honestly is to buy a camera that works best for you and what you shoot. In other words, get a Nikon or Sony. And before everyone flames me (I understand this is a mostly Canon site); I don't think that as a photographer you should adhere to the concept of "brand loyalty". No camera in my experience does everything perfectly. So you buy the system that will do everything you need to do today, and if your needs/style change in a couple years and that camera can't accommodate your needs then....then you switch to something that will.
A carpenter wouldn't buy a hammer, and stick with that brand/model forever just because it's what he's used to. If another company makes one with a better design/material/ergonomics that would work better for the job at hand....he'd invest in that one.
Case in point, I used to shoot Nikon ages ago (back when it was ~ the same IQ wise with Canon), loved the camera. Then I switched to shooting almost exclusively studio and a lot of beauty/headshots. The 70-200 f4IS and 135L were the ideal tools for my new style of shooting...so I ditched my Nikon equipment and went Canon. A couple years later, I'm shooting outdoors in crazy lighting situations and I NEED a camera with more dynamic range....so I bought an A7. Great size/weight benefits, IQ that blew away the 5dII and III, not to mention DR that allowed me to capture way more detail than I had been able to in almost 3years with Canon. The downside was their lens selection was crap. So I'll probably end up going with Nikon (unless the 5ds magically has more DR than early reports suggest) again.
Is it inconvenient? Not really. Lenses usually line up price-wise selling and buying used. Bodies are expendable. I'd say the switching every couple years is far less inconvenient than shooting and missing a shot or getting one that isn't as good as it could have possibly been.
If you have the $$$ then maybe consider multiple systems? I'm waiting on more reviews for the 5Ds, but I'm likely going to get a D810 next month. Even so, I know Nikon falls short in several areas (weak 24-70, overpriced 70-200f4, no pancakes, horrid video, etc)...so I'll be keeping my 70D to fill some of those holes. Again, today the manufacturers seem to be excelling in one or two areas and conceding the others to the competition. If you shoot different things, you might need to be willing to invest in different systems for different things if you want to do each thing you do the best you can.