The loan would still be a consumer-purpose loan and be subject to Regulation Z. However, the early TIL disclosures required by current 1026.19(a) would not apply because they hinge on RESPA applicability.
If you get an application like this on or after 8/1/15, the 25-acre RESPA exemption will be gone, but that wouldn't matter, because the TRID rules will apply, and you'd have to provide both a Loan Estimate and Closing Disclosure, whether or not there are buildings (or anything else!) on the land.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8