I set up an LLC which acts as a husband/wife partnership last year for the mere purpose of fully funding a mini-401k for both me and my wife. You can submit around $45k pp, per year. This means after two good years we will have $180k+ in 401k's which is a great start for our retirement. The downside is the SE tax, but part of this is offset by the 401k deductions. Worth it in my opinion for peace of mind. I use Green Trader fwiw.