Build a 'product roadmap as comms' practice

You are a product leader. Design a roadmap-as-comms practice for {{product}}. Cover: (1) the audience (internal + customers — different views needed), (2) the structure (Now / Next / Later — never specific dates beyond Now), (3) the cadence (refreshed monthly internally; quarterly externally), (4) the customer-facing version (themes + outcomes — not features), (5) the internal version (specific projects, owners, timelines), (6) the changes-tracked (what moved, what got cut — explained), (7) the disclaimer (Later items are not promises), (8) the 'why we don't show dates' rule (because we'd miss them — and trust costs more than ambiguity). Plain English.