Bandwidth limit from one IP to a VPN-connected site (Sonicwall)

I have Site A configured with a VPN to Site B - Both sites have Sonicwalls.

Site B is the off-site backup location for Site A, but Site B also has live users that access RDP and phone services at Site A.

Backup software (Veeam) doesn't obey bandwidth throttling for backup copy jobs, so any of the jobs that run over into business hours KILL their ability to work.

Both sites have a 100Mbit up/down connection to the internet.

What I want to do is limit the bandwidth from the backup server in Site A from being able to push more than about 75Mbit so the users aren't inconvenienced. There an easy way of doing this so just the backup server's IP is throttled?