Where to Invest Extra Investment Cash

I have about $1,000 from me (43) and my wife's (36) quarterly bonuses that I need to allocate towards our retirement savings but unsure where or what to invest it in. We follow the boglehead investment strategy (12% combined gross in my 403b TDF & 8% combined gross split in both of our T-IRAs (VTI=55%, VXUS=35%, BND=10%). Due to our budget, we are unable to contribute to Roth IRAs at this time and still hit our 20% yearly gross savings goal, but that is the goal in the near future.

We have already maxed out IRA contributions for the year and I don't receive another paycheck for the year where I would've just increased my contribution to allocate the $1,000.

I was thinking of just contributing it to a joint taxable brokerage and keep with the same (VTI, VXUS, BND) split, but not sure if that would be the right move. Any help would be appreciated.