One thing to try would be to use compression on the client resource via 
directive.
You have done right by breaking up the client save set, for the largest 
saveset that fails , check and see if there is any data you can retire to 
further shrink it.
You did not mention what type of connection you have to remote site and 
what errors do you have when backups fail ?If the problem is server 
hardware(on the client), could it get an update ?
Is it a time-out issues ? could you run the backups for the failed saveset 
at different time ? is it possible to move the saveset to another server 
at the same location ?
If the data transfer rate is low, you might benefit by backing up to disk 
type of device(ADV File-Device). ( If you already have disk backup 
licence, it may be worth a try)
Try compression option  first, you can consider the rest if it makes sense 
in your environment.
HTH

To sign off this list, send email to listserv AT listserv.temple DOT edu and 
type "signoff networker" in the body of the email. Please write to 
networker-request AT listserv.temple DOT edu if you have any problems with this 
list. You can access the archives at 
http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER