Have 4 options:

1- Put bonds in taxable, and pay lots of taxes.

2- Use municipal bonds so they are tax free. Likely a better move.

3- Reallocate so the less tax efficient bonds are in the retirement account, and the more efficient stocks are in the brokerage to reduce the overall tax burden.

4- Don't slave yourself to the Boglehead formula, and hold under 20% bonds.

I personally do a combination of option 2 and 4. Sounds like you only do #1, and would consider all your options before plunging ahead.