Andy, I totally understand your frustration in loosing so many photos and I feel for you. I guess one has to make changes to how you make sure you are protected in the future.
My answer to this is Backup Backup Backup. After providing support for some 28 years it always amazes me that so many users of PCs and Macs never perform backups of their hard drives. If something castrophic happens like your computer is stolen, your house gets flooded ( that happened here), the hard drive fails or one hits the wrong button in error and many more at a blink of the eye it is all gone. if you load photos direct to your iPad or other valuable data I suggest backing up your iPad at least once a week depending on usage
The most important asset is your computer which has a copy of your iPad if you value your data back up at least twice if not 3 times.
Note size of external drives should be same as your internal drive Label drives with a bright sticker so any one will know which drive is which.
External drive 1 ( yellow) Monday, Wednesday, Friday
External drive 2 (red) Tuesday, Thursday, Saturday
External Drive 3 (Blue) off site drive back up either weekly of monthly
Depending on your situation drive 1 and 2 can alternate off site.
If you are a light user make it week 1, week 3 week 5 on rotation.
Even if you have at least one back up it is better than nothing. The above system is a standard IT solution. It has worked for my Some 300 customers and it can work for you
As one user stated
" Think before you Sync"
So true the problem the OP had has nothing to do with iTunes it was about security of data in this case his huge photo collection. There are tools to recover and hopefully all will be ok. I hope the above helps other users from getting that cold feeling knowing you lost every thing. If you need more information on how to protect your data including any thing on your iPad let me know. Cheers
One more thing it does not matter if it is an Apple product like the iPad or a brand new tab from Samsung, or what ever the issue is the same. It is Not an iTunes problem it is all about prevention and protection of data regardless of what platform you use. This applies to mobile phones, laptops, towers net computers you name it.
I forgot at the very least for photos or important personal or business data use a 8 or 16gb flash drive and hang it around your neck or keep it some where safe but with out question off site from your business or home