You can calculate the value of the leased fee. Back to your books. Should be no trouble to value it once you understand what you are valuing. Sometimes you have get your head wrapped around it first.
http://nerej.com/fee-simple-vs-leased-fee-in-valuation-by-steve-hurlbut
https://mountainseed.com/2017/05/23/leased-fee-fee-simple/
AI has a PDF on the subject, google it up
However you are basically comparing the value between market rent and actual rents. The CA therefore acts as another check between the economic rents and market rents. You won't weight the CA normally for leased fee. It is an income problem.
Steve Hurlbut's article makes reference to the more extensive
https://www.appraisalinstitute.org/file.aspx?Document=Property_Symposium_Exp_12-21-17_-_Final.pdf. From reading this, the core issue seems to be in the conclusion:
"Potential implications of these proposals are that valuers would need to determine, and valuation reports clearly state, the estate (fee simple, leasehold, or life estate) as well as the actual or assumed interests associated with the real estate that are reflected in the valuation. Depending on the question to be answered by the valuation (i.e., the problem to be solved) for a property that is leased, or would likely be leased,
the valuation could be subject to the existing lease, subject to leases at market rates and terms, or as though vacant and available to be leased at market rates and terms. The valuer generally must consult with the client for the service to clarify which interests to value."
A little interpretation on the bold:
a) "the valuation could be subject to the existing lease" means we add or deduct the value of the difference between the current leases and market rates from the fee simple value if they are above or below market.
b) "subject to leases at market rates and terms" means we use the current leases, but apply market rates to their value,
c) "... as though vacant and available to be leased at market rates and terms." Oh, this is just great, now we are free to reconfigure the leases to achieve maximum profitability: Single Net, Double Net, Triple Net, Absolute Triple Net, Gross Lease, and so on! (I guess one could argue that the choice of lease type should not impact value, as the rate will be correspondingly adjusted, but I would say - that all depends). - But no, I am sure this is not what they meant, they most likely mean we have to calculate in vacancy, marketing and other startup costs. Who knows? Maybe they mean the whole works. - I guess that is up to the appraiser.
But then, (c) implies a new kind of basis for (a) and (b). That is (c) seems to be what you would want to consider for the income approach in your opinion of fee simple value.
In any case the discussion, at least as of the date of the article (December 2017) appears to be only a discussion. Makes sense, as it stands, (c) might make things a lot messier than they already are.