Backup the backup on long trips without laptop support

Hello fellow WD enthousiasts,
I could really use some help with a situation that I haven’t been able to solve. Long story short: is it possible to connect a My Passport Ultra HDD via USB to a My Passport wireless SSD and copy/transfer files from the SSD to the HDD using the mobile WD app (via iPhone/iPad)? And, if not, can anybody provide an alternative for my use-case that wouldn’t break the bank?

Background / use-case
This summer, I’m going on a 14 days cruise using a GoPro Hero 7 black to shoot a lot of footage. Shooting 4K@60fps with protune on, guestimation is this would produce 2-3 TB of raw footage. Now I don’t wanna take my laptop and backup storage along, nor do I like to select or edit during the trip to trim storage requirements. In addition, I also can’t rely on offloading data to the cloud, as wifi availability on a cruise ship (and in most ports, for that matter) is not guaranteed, not up-to-speed and/or extremely expensive. This creates an interesting challenge.

Because of ease-of-use, my original plan was to do single-button backup’s during the day on a My Passport Wireless SSD that I could carry around in a backpack. Problem is, you can’t really delete/re-use the micro-SD’s until you offloaded the MPwSSD, otherwise you would still end-up with only one copy. Alternatively, 2-3 TB of micro-SD cards is too expensive as well, as are two 2TB MPwSSD’s, plus, what to do if I would go over the 2TB version limit?

The best (theoretical) solution I’ve come up with untill now (but is it?) is to use two relatively cheap redundant My Passport (ultra) 4TB’s HDD’s to offload the MPwSSD to, leaving those in the cabin during the cruise and taking them home in hand luggage and check-in bagage respectively flying home. It’s just not clear to me whether this is even possible. Or what a viable alternative would look like.

All suggestions will be greatly appreciated.

You really cannot avoid the computer requirement. Look in to a small computer (at COSTCO) with a decent size. HD you can store data on and eliminate the outboard HDs.