Increased Rights to Records in Embedded/Related Lists when Assigned to a Task

[Peter26]

Greetings,

In one of our custom apps, we have several situations where we have forms from a Task-extended table that have Embedded/Related lists. In general, most users should have read-only access to records in the tables represented by those lists. 

However, if a user is assigned to a Task Record from our Task-extended table, either directly or through an Assignment Group, we'd like to increase rights to include "create" and "write" permissions for the records in the tables represented by the lists. 

I've considered the following approaches:

1. ACL Only Approach
   
   1. The issue with this approach is that, within an ACL on the Related List table, I won't have access to a specific Task record to determine if the current user is assigned to it or not
   2. My only recourse, then, would be to query the entire Task-extended table to determine if the current user is assigned to at least one task -- which might be performance-intensive
2. ACL and Client Script Approach
   1. I'd create "write" and "create" ACL's that are open to everyone, then restrict access at the view level via a Client Script
   2. I see two issues with this:
      1. Not very secure; savvy users who know how to get to stand-alone list views for the list tables will have rights there that they shouldn't
      2. May be difficult, and/or present a clunky user experience, to control access to records in Embedded/Related Lists through a Client Script

Looking to see if anyone has had experience dealing with this situation and/or has any ideas on best practices for addressing it. Thanks!