I'd be inclined to not worry too much about if you end up taking both. Only you know what is more comfortable for you for given riding temps, I know with me I just like having the hiking type pants for off bike non bikey look, plus being not tight, mosquitoes won't get me through them if I just have my tights on. Some places the bugs can be horrible.
As you say, the majority of time you'll be in bike shorts.
All the best with this final decision, but most importantly have a great adventure.
The other thing the OP needs to keep in mind is that if your only pants are something you rode in they could be wet, dirty/muddy, etc., at the end of the day. Like you, I like to have something comfortable and loose to put on at the end of the day. My convertible hiking pants fit the bill. And the base layer, which I’ll wear under the pants with the legs zipped off, is akin to a nice blanket for my legs when it’s cool out.
And yeah, I can’t think of a few places on the MT section of the TA alone where the mosquitoes can be voracious when the OP will likely be there. And they can bite through tight clothing. Outside of Wisdom the GF and I got set as we were riding up a short incline at the entrance to a cattle ranch with standing water by the side of the road. And walking around town in the evening was tough because of the suckers.