It would help if you said what the contents will weigh. If it exceeds the airine carry-on weight limit,that is the end of this conversation. Some airlines have as low a limit as 11 lbs. and 15 lbs. is common.

If you meet weight requirement then you need to say what size pack you need.

It appears you understand the importance of torso length and that a 'waist belt' is not a real 'hip belt'. Few people do, so you are ahead of the crowd in that. Few 'travel packs' do much to allow for varying torso length. One you could look at is the Osprey Farpoint 40. http://www.ospreypacks.com/en/produc...ng/farpoint_40