Entering the United States on a return ticket from Mexico under the VWP

I am a UK citizen intending to travel to the United States via Mexico in order to see my fiancee. I will spend the necessary fourteen days there before traveling onward to the US in order to circumvent the travel ban that is currently in place. I have a valid ESTA and seek to be admitted under the Visa Waiver Program.

My planned itinerary involves two return tickets, one between the UK and Mexico, and the other between Mexico and the United States. The plan is that I will travel to Mexico, spend the necessary fourteen days before traveling onward to the US on a separate return ticket, which would then take me back to Mexico to complete the return leg of my initial ticket. This is significantly cheaper than booking three separate one-way tickets that would allow me to fly directly back to the UK.

However, it's just come to my attention that the eligibility requirement under 8 USC 1187(a)(8) may prevent me from doing this. It reads as follows.

(8) Round-trip ticket

The alien is in possession of a round-trip transportation ticket (unless this requirement is waived by the Secretary of Homeland Security under regulations or the alien is arriving at the port of entry on an aircraft operated under part 135 of title 14, Code of Federal Regulations, or a noncommercial aircraft that is owned or operated by a domestic corporation conducting operations under part 91 of title 14, Code of Federal Regulations).

The round trip ticket is defined under 8 CFR 217.2(a) as follows.

Round trip ticket means any return trip transportation ticket in the name of an arriving Visa Waiver Pilot Program applicant on a participating carrier valid for at least 1 year, electronic ticket record, airline employee passes indicating return passage, individual vouchers for return passage, group vouchers for return passage for charter flights, and military travel orders which include military dependents for return to duty stations outside the United States on U.S. military flights. A period of validity of 1 year need not be reflected on the ticket itself, provided that the carrier agrees that it will honor the return portion of the ticket at any time, as provided in Form I-775, Visa Waiver Pilot Program Agreement.

So far, this is no problem. However, the restriction mentioned under 8 CFR 217.2(c)(1) is what leads me to doubt if I am actually admissible under such arrangements. It reads as follows.

(1) Applicants arriving by air and sea. Applicants must arrive on a carrier that is signatory to a Visa Waiver Pilot Program Agreement and at the time of arrival must have a round trip ticket that will transport the traveler out of the United States to any other foreign port or place as long as the trip does not terminate in contiguous territory or an adjacent island; except that the round trip ticket may transport the traveler to contiguous territory or an adjacent island, if the traveler is a resident of the country of destination.

The problem here is that my ticket to the United States is a return ticket to Mexico, making it seem as if I could be falling foul of 8 CFR 217.2(c)(1) as my ticket does indeed terminate in a contiguous territory in which I am not a resident.

Does the fact that I have a separate return ticket from Mexico to the UK less than eight hours after returning there overcome this ineligibility? It seems to depend on whether the trip refers to my travel itinerary as a whole, or to just the the aforementioned "round trip ticket" required under 8 USC 1187(a)(8).