I have my IRA at Ameritrade and I want to start using a 3 fund portfolio. Ameritrade offers VTI and BND as fee-free funds, but not VXUS. They do offer these Vanguard international funds fee-free though: VEA, VEU, VGK, VSS, VWO. Would any of those (or combo of those) work as a good substitute for VXUS?