There's very little exposure with a trust, as no one knows the beneficiary and the trustee is protected by law.

The beneficiary is a Florida LLC (FLLC1).3.

The beneficiary would have to open an inherited self-directed IRA; the assets will be rolled over there.

And the transfer is really easy, no probate (just assign a beneficiary), and you don't even have to re-record a deed...But back to your question about one property all cash or leverage? 

I would like to sell a rental property and do a 1031 exchange to buy a property from my mother's estate (I am a beneficiary).

in 2024 For Medicare Part B (Medical Insurance):The maximum monthly premium for high-income beneficiaries is $594.00.

However if your beneficiaries are your the priority  I would still recommend focusing more of your attention and resources on buying great real estate and being a great operator.

These are listed as beneficiaries to a trust.

I know legal ownership and beneficiaries can increase that coverage in a number of different combinations, but are there ways you can think of to expand coverage specifically with the solo 401k's?

There is also a strategy that places the property in a land trust with the LLC as the beneficiary.