How to create an USB stick with Win10/Linux dual boot?

I would like to put Windows10 and Manjaro Linux on one 32GB USB stick, with a nice menu at bootup that asks me what I would like to boot, and then either go install Win10 or boot up Manjaro Live.

I tried at least 5 different tools but none of them work, could also be that I chose the wrong options.
I tried SARDU, WinSetupFromUSB, XBoot, MultiBootUSB, YUMI (non UEFI version).
Didn't write down what went wrong since I didn't know I would make this thread and don't wanna go through it all again If I don't have to, especially since it would degrade the life of the stick If I constantly write tons of data to it...

Either manjaro doesn't show up in the bootmanager, or when trying to start manjaro the screen stays black, or when choosing to boot the windows install it says the computer is corrupted and needs to be repaired (which of course isn't true, there's just something wrong with how the ISO/install was written by the tools).

Both ISOs work when written in isolation to the stick by Rufus.

I tried multiple guides but I guess they're all outdated? I have no idea...

Can anyone point me to a working guide that still works in 2019 or tell me the exact options I need to use to make this work?
Do I need to format the stick as NTFS or FAT32? UEFI or BIOS? MBR or GPT?
I think NTSF is windows only, so manjaro wouldn't work with it? But FAT32 is too small to fit Win10 on it (4.4GB).
I don't know what to do, nothing that I tried makes both work. It's either one or the other.
Does it even work? Doesn't windows and linux use totally different boot records boot loaders, boot methods whatever it's called?

Sorry If I don't know the correct terms and methods but most guides just say "check this box and press this button, now it should work" without explaining when to use what options or why or how it works. And when it doesn't work... well...

These are the two files I would like to put on the stick:
manjaro-kde-18.0.2-stable-x86_64.iso
Win10_1809Oct_English_x64.iso

You might try EasyBCD (NeoSmart Technologies). It's a bit involved to create a mult-boot USB with it since it's mainly a BCD editor, but it's grub based and should be able to handle UEFI boot without a problem. I've used it to make multi-boot thumb drives, but I have to admit that was on MBR not UEFI.

To use it you have to point to the USB drive instead of the system drive and make the USB media bootable beforehand, which is actually easier for UEFI compared to MBR.

Horscht said:

But FAT32 is too small to fit Win10 on it (4.4GB).

If you're making an install USB, the iso gets unpacked. There would only be a problem with the Fat32 4GB limit if any individual file in the iso was > 4GB.

Note that even though Fat32 has a max partition size of 2TB, Windows seems to impose its own limit of 32GB, so you might have problems with trying to format (say) a 64GB USB as Fat32.

Try Steve Si's "Easy2Boot" (Easy2Boot).

Far and away the best platform for multibooting from ISO's.