He would like to move this investment into an irrevocable trust for estate planning purposes.

Some examples of the filter parameters include:Husband and wifeRevocable/Irrevocable TrustFamily TrustJoint TenantsEstateCompany/CorporationPartnershipThere are many additional options.

Revocable or irrevocable trust?  

Not sure if you're talking the trusts are general grantor/family trusts or if they're irrevocable trusts. 

A revocable estate planning trust is now irrevocable after grantor passes away. 

Each bid is by law an irrevocable offer to purchase.

Pursuant to Section 3712 of the Revenue and Taxation Code, the tax deed conveys title to the purchaser free of all encumbrances of any kind existing before the sale, except:• Any lien for installments of taxes and special assessments, which installments will become payable upon the secured roll after the time of the sale.• The lien for taxes or assessments or other rights of any taxing agency that does not consent to the sale under this chapter.• Liens for special assessments levied upon the property conveyed which were, at the time of the sale, not included in the amount necessary to redeem the tax-defaulted property.• Unaccepted, recorded, irrevocable offers of dedication of the property to the public or a public entity for a public purpose, and recorded options of any taxing agency to purchase the property or any interest therein for a public purpose.Any federal Internal Revenue Service liens that, pursuant to provisions of federal law, are not discharged by the sale, even though the tax collector has provided proper notice to the Internal Revenue Service before that date....according to that, California tax sales doesn't seem pretty free and clear to me.

These eventually work their way down to a generation skipping trust that is an IRREVOcable trust for asset protection set up for grand kids and future generations.

. - Presumptions.It says in part: "...All contracts, options, or other devices not based upon a substantial consideration, or that are otherwise employed to permit an unlicensed person to sell, lease, or let real estate, the beneficial title to which has not, in good faith, passed to such party for a substantial consideration, are hereby declared void and ineffective in all cases, suits, or proceedings had or taken under this chapter; however, this section shall not apply to irrevocable gifts, to unconditional contracts to purchase, or to options based upon a substantial consideration actually paid and not subject to any agreements to return or right of return reserved."

If your land trust was the Irrevocable type, you would be required to be much more strict as you will now have to be VERY specific as to the cashflow.