Scaling up: Dealing with supply chain lag for Cumaru

I have been quoting mostly Ipe for years, but with current lead times stretching to eight weeks on 1x6 stock, I am pushing more clients toward Cumaru. The problem is the price volatility. I have a 900sqft build coming up in coastal South Carolina and my local supplier just hiked the board foot price by 12 percent without warning. My initial bid was based on old data and I am terrified of eating my margins if I don't secure the material now. Are you guys writing 'escalation clauses' into your contracts to protect against lumber price swings, or do you just add a 15 percent buffer to your material estimates to be safe? This heat is brutal, and I don't want to be losing money while working these 10-hour days in the humidity. Any advice on managing these client conversations regarding mid-job cost adjustments would be appreciated.