Even after you overcome the current Workstation Sync issue, I foresee the whole user experience as being way too slow for comfort. And printing a report will take ages. At Sage I contributed quite a bit to the SPM content. The section about VPN, ping times (the 1800ms Microsoft rule of thumb), shared internet vs Point-to-Point (P2P) connections, VPN alone too slow unless accompanied by RDP, etc is largely mine. I don't know what it says today exactly but I'm thinking your bigger goal should be to find a way to justify Terminal Server / RDS or Citrix and running Wkstn Setup on that hosted VM/box.
In the non-optimal setup you're being forced into, you could document the slowness in terms of start up time, opening screens, moving from tab to tab within a screen, and printing. Just print an A/R Aging report and record the slowness. Then note the time to do same stuff on their current un-upgraded version.
It's also helpful for the hosted IT people to speak with Sage 100 IT people like several in this group, some of which do their own hosting. It's a trust thing and they become much more receptive when you can speak their language. I sound vain but I've found for myself when I have that 20 minute friendly conversation with IT giving them my background creds and experience and explaining the 100 architecture, and using their terminology, it has made the key difference to swing the decision in the direction we want as the client's trusted advisor.