I've had the same experience as
@DRAX in my canyon (6'1 and change, here). I recognize that's a ways off 6'4", but while I don't fit in a Tacoma, I fit in the Canyon with room to spare with an Akubra on, so that adds a few inches to the top of my head. Like Verkstad, I bump my leg occasionally -- much of that has to do with seat positioning though, as the same thing happens on my full size which is much more roomy. Plus, the Canyon seat goes really low and quite far back, so there's plenty of room for adjustment beyond what I use and I have no question at all about headroom for someone a bit taller than me. And as you probably know, the Canyon interior will be the same as the Colorado, even the ZR2 (more or less, depending on options), so there are quite a few configurations of that platform you can choose from. However, the ZR2 has a few hundred lbs less payload, which brings me to my next observation.
These trucks are great, but they max payload at around 1500 lbs, while many slide-in campers that are marketed and sold as "for mid-size trucks" use up 90%+ of that capacity as their dry weight (there is a recent thread on this forum about that very issue). That means by the time you add yourself, some passengers, and some gear, you have well outstripped the intended capacity of the truck. This may not at all matter to you, and most people don't give it much mind, but it's worth mentioning. The more minimalist canopy campers tend to be more appropriate for these trucks -- Alucab, GFC, Vagabond, etc. -- than the traditional slide ins like FWC, Lance, etc. with lots of bells and whistles. If you wanted a larger slide-in camper, look to the full-size realm as
@Jnich77 has suggested, and even then you may still run up on payload issues and need to go HD depending on what camper you want. If your priority is off-road nimbleness, just be aware that will limit your camper options much more than the marketing materials will acknowledge.
Anyway, that's three votes for a GMC product as the interior is really well done for this class in terms of fitting taller folks. I'd say it's worth trying one out to see. I have had very good experiences with my GM products and all have been fairly reliable -- they aren't the best, but they are far from the worst in terms of reliability. I absolutely love my Canyon for the comfort, power, and off-road capability (I'm rapidly warming up to the auto-locker...it just sorta works when it needs to -- and this thing is like a mountain goat off-road, very nimble and plucky) and recommend them whole heartedly.
