One tidbit of a suggestion from my experience with my first bus (RIP):
We did not have any passenger seats specifically set up for traveling. What we had, was a dinette set -- a "Denny's booth" -- on each side. The booths were simply bus seats, two of them turned around, and home made tables. "Seating eight for dinner" was the priority. We figured we could always suffer thru getting there.
Turned out, we loved the dinettes for traveling with up to four passengers. The passengers liked lounging sideways on the seats, and they liked resting their arms on the tables.
So my suggestion is to not bother with "travel seats", unless you are going to have a lot of passengers.