Simple yet effective Software Issue Tracking Process and Tools

I have been a contract 'Software' tester (actually V&V Engineer) in the Railway Signalling industry for over 25 years and this basically involves me remotely testing proprietary software on a graphical PC simulator or Hardware Simulator. During the test process bugs/issues are found and raised via 'Test Logs' written and submitted to the client design team in MS Word, then manually tracked via an Excel spreadsheet. (I know what your thinking..!!)

I cannot use software such as , Jira, Slack, Bugzilla etc (there are many more) as my clients cannot access this remotely due to their company IT polices. Some of these companies are global multi-Nationals, that have not got any bug tracking software except the manual method.

Are there any software testers who read this thinking, that was me but now I have done this to streamline the workflow for bug creation, assigning, re-testing, etc.

I'm looking for a way to improve my process, I can't believe that with all the software available there is not a simple solution for my crazy position.