I would also be concerned about potential taxable event due to loss of job. I realize you think your job is stable but nobody really knows if that’s the case. A blend of qualified and non qualified planning is usually a good idea for many reasons. Get some current tax breaks (401k) but also have liquidity (non qualified planning). Most people don’t realize you can actually access roth IRA contributions penalty and tax free pre 59.5 (not converted dollars - from traditional ira) because you’ve already been taxed on those dollars. Plain old vanilla non qualified or 529 (preferred for tax leverage) will help for college.
I’ve seen folks use the 401k the way you suggest. It’s just a bit risky so be careful. Also, the 50k limit doesn’t help you too much.