FOO for business owners?

Last year I made my side hustle (an ecommerce brand) my main job. Modest numbers in 2025 but it’s growing quickly and if it holds up, together with my spouse’s W-2 I’m looking at potentially crossing into the 32% or even 35% marginal tax bracket in 2026. Company is a single member LLC and for 2026 I’m now looking into opting into taxation as S-Corp.

We’re in our 30s. MA. 2 young kids. No debt, no house. $400k HH NW. Probably around step 7 of FOO.

What are the classic ways to optimize my spending & taxes in this constellation? Basically a FOO for business owners?

Things that are already on my mind: S-Corp, solo 401k, (mega?) backdoor roth, buying a house & itemized deduction.