There seems to be a bit of a contradiction. IAS 17 permits FV under IAS 40 if the lease is classified as a finance lease. This assumes all the risks and rewards are transferred and should transfer the asset at the end of the lease. This is different than what you are stating where you intend to only hold for 25 years and not take possession of the asset. Under that scenario I would argue this is not a finance lease and not permitted to be accounted for as such - making the FV rule inapproprioate for you.
Below is the criteria to be a finance lease from IAS 17:
Whether a lease is a finance lease or an operating lease depends on the substance of the transaction rather than the form. Situations that would normally lead to a lease being classified as a finance lease include the following: [IAS 17.10]
the lease transfers ownership of the asset to the lessee by the end of the lease term
the lessee has the option to purchase the asset at a price which is expected to be sufficiently lower than fair value at the date the option becomes exercisable that, at the inception of the lease, it is reasonably certain that the option will be exercised
the lease term is for the major part of the economic life of the asset, even if title is not transferred
at the inception of the lease, the present value of the minimum lease payments amounts to at least substantially all of the fair value of the leased asset
the lease assets are of a specialised nature such that only the lessee can use them without major modifications being made
Other situations that might also lead to classification as a finance lease are: [IAS 17.11]
if the lessee is entitled to cancel the lease, the lessor's losses associated with the cancellation are borne by the lessee
gains or losses from fluctuations in the fair value of the residual fall to the lessee (for example, by means of a rebate of lease payments)
the lessee has the ability to continue to lease for a secondary period at a rent that is substantially lower than market rent
That is why you are permitted FV under finance lease since you effectively "own" the asset under the accounting rules.
IFRS is not my area of expertise but is how I read the guidance. What have I missed?