An LOI won't satisfy a preleasing condition anywhere I'm aware of. Construction lenders are underwriting a cash flow stream they can foreclose into, and a non-binding LOI gives them nothing to attach. What they'll accept is an executed lease with a defined commencement mechanism tied to delivery, rent commencing on a stated event, and a tenant credit they can evaluate.
The structure that usually resolves your specific deadlock is a lease executed now with a condition subsequent and a hard outside date. The tenant signs, and the lease terminates without penalty if the building permit isn't issued by a date certain, say 12 months out. Lenders vary on whether they count that toward preleasing, and many will if the outside date sits comfortably inside their own timeline and the termination right is narrow rather than a general out. Get that in writing from the lender before you spend legal fees drafting it. The tenant gets its protection, you get a countable lease.
Your $85/sf TI is the number I'd worry about more than the preleasing. That's $1.53M on the anchor space alone, nine percent of total cost, and medical fit-out routinely exceeds allowances once you're into medical gas, extra plumbing chases, and lead-lined imaging rooms. Confirm whether the lender is including TI in the loan budget and whether it counts in the LTC denominator, because if TI sits inside 62 percent LTC your real equity requirement on the shell is higher than it looks.
The other exposure is the reserve. At SOFR plus 325 over 30 months, the interest reserve was sized off a forward curve someone chose. If rates hold higher than that curve, the reserve depletes before stabilization and you fund the shortfall out of pocket, which is typically a covenant obligation rather than a choice. Ask for the reserve sizing assumptions in writing.
And underwrite the guarantee behind the anchor. A five physician group is not a health system. If the lease isn't guaranteed by the individual physicians or backed by something with a balance sheet, the lender may discount that 18,000 feet regardless of what the document says.