To keep the size of the profiles down, change the paths for temporary and user files using either a system policy (recommended) or modifying the relevant registry keys (not really recommended!).
You could schedule in a simple folder delete batch file using the at utility to clear the profiles down - but my preference is for roaming profiles. You could then implement the registry key HKLM\Software\Windows NT\Currrent Version\Winlogon\DeleteRoamingCache: REG_DWORD: 0x1 (It doesn't exist by default, but the API does!).
Kick your network guys to sort out any networking issues - once you've got roaming profiles in place, you have more control over your implementation ;-)
Hope this helps