I think you would really enjoy the space/flexibility a toyhauler offers. I don't find toyhaulers to be dark or cramped.... our previous travel trailer had a separate garage and a slide out. Our current 5er has 2 slides and a separate garage that is separated with a glass sliding door and 2 huge windows in the garage. I think if you find the right floor plan the things in your negative list would go away.
The only negatives I can really think of are (I'm biased of course, we've never owned anything but a toyhauler)
-They are heavier than a similar sized travel trailer. So, meaning, you'd need a bigger truck. But it looks like you already have one.
-There's less comfy living space. Our old TT didn't have a place at all to sit down and relax other than the dining bench, but that was a model problem. Even now we just have the one couch. I'm sometimes envious of people with a similar sized regular 5th wheel with their cozy living rooms in the back. But, if you plan to spend most of your time outdoors, this doesn't matter.
