Need a new external HDD that still works by Firewire under Tiger 10.4.11

Hi Everyone!

This is a continuation of a new question from my other posting (https://discussions.apple.com/thread/6866622) as I would like to discuss this as a new topic so if I get answers I can give proper acknowledgement and rewards for them.

I have a Mac G4 PPC chip, running 10.4.11. I cannot upgrade to Leopard as it does not have the Intel chip (who'd knew I'd need it?)

The internal HD is only 60 GB in size.

Long ago in 2005 I got two external 500 GB HD's manufactured by "G-Drive" company for holding the iPhotos and been filling them up.

Now I need larger units or more of the same and no one is making them for 10.4.11 brand new (I don't want to get someone's old Ebay one for obvious reasons as who knows when it will fail---that is why I have two identical units backing up the Mac G4 plus holding the iPhoto libraries. That is in case one fails I have the other one.)

But I'm running out of space on both of them. They are G-Drives which were good back then, but today you need 10.5 Leopard to buy any new ones with Firewire connections for the G4.

I did find one new company that is making replacement ones, but... its a big but..

I am also using (since 2005) Bluetooth mouse and a Bluetooth connected keyboard instead of the laptop's own touch pad as I never could get the hang of using that touchpad vs. a real mouse, and typing on the cramped keyboard is bad on my hands, so I have a wide, split Ergonomic one instead.

That all works just fine, but the replacement company has a negative for their drives. For some reason everyone reports that they interfere with their Bluetooth devices. They cannot upload from phones to the computer etc while the Drives are connected, even if hidden under the table, as they say they interfere with the Bluetooth signal.

So I would be suddenly without a mouse or keyboard, trying to move/save/write files from a phone unable to bluetooth them over, and that is not the best situation to mistakingly save/copy names etc when doing that. So I can't take that, nor can I trust someone's unused in the Box old G-Drive as it is just as old as the ones I have and they can fail too.

Which is a good reason for me to get new HDD's that are larger. ( I hope Tiger can "read" 1 TB drives, else I'll just have to share the data with more 500 GB ones).

Anyway----the problem is serious as no matter how much I want and need to upgrade the computer to something more modern, I can't afford it now or in foreseeable years from now, so I just have to keep limping along with what I have.

Any suggestions? Any work arounds to the "Startup Disk is Almost Full" message without damaging the data and internal HD of the G4?

Thank you for reading this!

Mac_Help