How to withdraw SEP IRA and TSP funds prior to 59.5?

[Fi365]

Apologies if this has been written about elsewhere... Please point me in the right direction.

I contribute to a SEP IRA through my one-woman-show LLC.

My husband contributes to a TSP through his Federal government job.

We also contribute to our traditional IRAs.

Our current thinking is to work until 55 AT THE LATEST because that's when he'll have his 30 years in and get full pension benefits. Although our investments will be 25x our expenses around age 38-40, so we may forego the pension and go live life before that.

I know that we can withdraw our IRA funds (Roth conversion ladder). What about SEP IRAs and TSPs?

Tips appreciated! Thank you!

P.S. I'm considering opening a solo 401k for my business instead of a SEP IRA because there are higher contribution limits (I could contribute ~$50,000/year to a solo 401k vs. ~$30,000/year to a SEP IRA). Anyone know whether solo 401k funds can be accessed prior to 59.5, and if so, how?

[Cognitive Miser]

A new bill was just signed into law that improves Feds' ability to withdraw from their TSP accounts.  Previously, you could only take ONE partial withdrawal - your second withdrawal had better be the entire account balance.  So it was not good for Roth laddering.  Give the TSP a couple of years, and apparently it will be possible to use it in this manner.
https://www.tsp.gov/whatsnew/Content/index.html
https://www.tsp.gov/PDF/formspubs/tspfs10.pdf

[seattlecyclone]

You can do Roth conversions from a SEP IRA just the same as from any other IRA. It can work great for the Roth ladder.