I think you could but to do it legitimately you would each have to have a trust set up that can be the owner of the ibonds... if you or your spouse already have trusts then you would be all set.
If you create trusts for this, perhaps one could name them "MonteCFO Trust to Sidestep ibond Purchase Limits" and "MonteCFO DW Trust to Sidestep ibond Purchase Limits".
I wonder if the beneficiary of the trust upon the grantor's death is the spouse if you could register the spouse (personally) as the beneficiary? You might also at some point need to provide Treasury Direct with a copy of the trust (I recall when we set up my Dad's trust accounts with Vanguard that we needed to provide them with a copy of the trust document).
I'm not sure what other complications that using trusts might create.