Sounds to me like it’s not a year long bike trip, but working on the road and being fortunate enough to bring a bike. Nothing wrong with downsizing and simplyfying on such a trip. I guess it’s up to everyone’s priorities. I wouldn’t bring two bikes either.
As a general remark your post sounds quite bitter and envious (not sure if that was intended).Probably a bad attitude in a cycling forum since a lot of people spend their money on their hobby according to their own liking. It actually made me chuckle a little bit seeing all your $$$ signs. The gravel bike including the power meter costs probably less than the average carbon wheelset people talk about here. OP also didn’t ask about an opinion on his/her live choices or automotive purchases but just about help choosing between two bikes. So back on topic: I recommend take the gravel bike.