The wiki Comparison of text editors lists some other editors that suport large files, but I will deal with with EditPad Pro and UltraEdit.
The installer includes 64-bit version and 32-bit version and selects appropriate version during installation. You can pass /32 to the installer to force 32-bit installation
Built-in forum (login includes license information), forum is available only after purchase.
Explorer context menu for all files: HKCU\Software\Classes\* (it will be automagically merged for current user to HKCR\Classes), save this into *.reg file.
Windows Registry Editor Version 5.00 [HKEY_CURRENT_USER\Software\Classes\*\shell\EditPad_pro] @="Open in EditPad Pro" "Icon"="\\\\pc10010\\G\\Portable\\EditPad Pro 7\\EditPadPro7.exe,0" [HKEY_CURRENT_USER\Software\Classes\*\shell\EditPad_pro\command] @="\\\\pc10010\\G\\Portable\\EditPad Pro 7\\EditPadPro7.exe \"%1\""
Portable version does seem to store configuration local to the computer where it runs, in \Users\<user>\AppData\Roaming\JGsoft\EditPad Pro 7. I did not found any documentation. Maybe this is caused by sharing the USB as read/only.
UltraEdit, $80 (Windows, Linux and Mac), $60 (UltraEdit Mobile), $90 (Desktop + Mobile bundle)
There could be some limitations of Undo, check.