Remittance Strategy for $210k+ CRA Liability: Asset Preservation vs. Liquidation

I am finalizing the filing of several returns resulting in a total tax liability exceeding $210,000. Based in Toronto, I am currently preparing to negotiate a structured payment arrangement.

Financial Context:

• Status: Voluntary filing/finalizing; no enforcement action or legal warnings issued yet.
• Cash Flow: Stable, high-income profile with the ability to commit to aggressive monthly payments.
• Asset Base: Significant equity in investment positions. Due to current market conditions and tax-loss harvesting schedules, liquidation is not the preferred path.

Seeking Experience-Based Insights On:

1. Financial Disclosure Requirements: For balances >$200k, does the CRA typically mandate a full Statement of Assets and Liabilities (RC5) before agreeing to a plan that exceeds 12 months?
2. Asset Liquidation Pressure: In recent cases, how aggressively has CRA Collections pushed for the liquidation of non-registered accounts when a viable monthly payment plan (covering principal + 7% prescribed interest) is offered?
3. Third-Party Representation: Is there a measurable advantage to having a Tax Lawyer initiate the contact to "buffer" the initial financial disclosure, or is direct transparency usually sufficient for a first-time arrangement?
4. Enforcement Triggers: At what duration (e.g., 24+ months) does the CRA typically move from a standard arrangement to demanding a security interest (lien) on assets?

I am looking for responses from professionals or individuals who have managed similar six-figure balances.