1) Used a 16GB fat32 formatted SanDisk USB. Any USB less than 32GBs seems to work well with fat32.
2) Open the ISO file and copy the EFI, boot, and porteus folders to the 16GB USB.
3) Booted the USB to the Porteus Graphical window, then moved down to the "Text Mode" option and selected it. At the "porteus login:" prompt type root. At the "Password:" prompt type toor.
4) Now, at the "root@porteus: #" prompt type startx. Need to be root in order to make some moves later.
5) Used a 32GB SanDisk USB for this next stage...Samsung USBs also work, but some other USBs seem to have issues with the ext4 format. Also, any bigger sized USBs work this way. Using GParted I prep the 32GB USB by creating a new msdos Partition Table. (If you have never used GParted, then it is time to learn. Practice. Practice. Practice. Ask the Forum if you have issues with it.)

6) Then create a 360MiB fat32 partition. This size has worked well for me.
7) Create an ext4 partition using the remaining space on the USB. On the 32GB USB it shows 28.29GiB.
8) Open the 16GB USB's window.
9) In separate windows, open the new 377MB (360MiB) volume window, and the 30GB (28.29MiB) volume window...they are listed under the "My Computer" column.
10) From the 16GB window: copy the EFI & boot folders to the 32GB USB's 377MB (360MiB) fat32 partition.
11) From the 16GB window: copy the porteus folder to the 32GB USB's 30GB (28.29MiB) ext4 partition.
That's it, and Yes, Porteus is incredibly flexible!
No scripts were needed. No Flags had to be added. No "savefile" needs to be created.
This method has worked on three of my test computers. It didn't work on a 12.2” Samsung Chromebook Plus V2 XE521QAB that I have converted to a Linux Laptop/Tablet/Sketchbook.