If your clients are using SQL Server 2005, I think, and later, you could use the .net framework and SMO to create an exe that restores the backup or runs the scripts that they can run from the commandline.

I am an application developer, and we use Advanced Installer (http://www.advancedinstaller.com/) to install our ASP.net applications that are all front ends to a SQL Server 2005 or later database. The MSI that it creates executes the SQL scripts against the SQL Server. It works pretty slick, so this would be another option. You can use this in two manners: 1) Generate scripts for your database, including data, and have the MSI execute the scripts, or 2) Have the MSI restore your database. I have done the option 1 with success, but knowing the functionality of Advanced Installer, option 2 is doable.

You may also want to make sure that you are compacting your backups to help with size.

Hope this helps,

Jim