No problem.
As long as you don’t use iCloud Photo Library, deleting a photo on one device will not effect the other’s library. Actually you can use it on one device. Just don’t enable it on both.
You can still use the Photo Stream. This allows each device to see the last 30 days of photos from the other device. The photos are not saved past that on the secondary devices, and deleting the photos from the Photo Stream album will not delete them from the original device’s main library (thought it may delete them from the Photo Stream album. Been a while since I’ve used it, so I’m unsure of the exact behavior details.
You can also enable Shared Albums on both devices, letting you create and sync only certain albums between devices (and others). Good mostly for sharing stuff with family and friends.
Keep in mind that if you are not using iCloud Photo Library you’ll want to make sure you have Photos enabled in your backup. Depending on how big your photo libraries get, you may need to purchase extra iCloud space (or do old fashioned backups in iTunes on a computer).
Do not neglect some kind of backup for your photos (and other iPad content).