While syncing RDR2's complex story missions is a nightmare, basic position and ped model syncing for free-roam using a custom P2P socket plugin is definitely achievable. Existing frameworks like RedM already handle multiplayer ped streaming, but a lightweight ASI plugin specifically tuned for single-player campaign free-roam would be amazing for casual exploration without setting up dedicated servers. The biggest hurdles will be managing host-client entity ownership, sync smoothing to prevent rubberbanding, and avoiding crashes when interacting with local world events.