It will depend on how you want to travel and only you will know.
Think about what you NEED to take vs what you WANT to take and go from there.
Put all the stuff you NEED to take and lay it out. if you dont, you will probably end up getting a bag too small for your NEEDs and end up looking/buying all over again.
then go looking for a bag.
gather up all of the stuff you want to bring and take all that to your local photo shop and look for bags. Note that you may find something at your local goodwill or 2nd hand store or Target or places like that. I noticed that at a couple of our local shops they had some used cases along with many film SLRs. Im sure the film camera market has dropped out where you live too, so you may find something used in your area. I would also go to luggage stores too since they will carry not just luggage, but also bags.
This is how i did things when i had 2 SLRs hanging off my neck when i was into photography many years ago.
i made/modified some hard cases to clip onto a belt. I made a heavy duty (1.5" wide) leather belt and put some spring clips on each side near my right and left hands. The clips are like the ones on a dog leash. The cases, usually come with "d" rings on them, if not, i attached some to the cases. I could then clip the cases onto the belt and my hands were free since i had the cameras around my neck. If i didnt want both, i didnt have to bring both, but just bring the ones i wanted.
Since you have time, i would do some dry runs with what you can find locally but gather what you want to bring so you dont have to find a larger/smaller case if you forget or add something. If you can find one that collapses, i would opt for that unless you dont mind it taking up space in your carryon.