J.B. has some good advice, Chris. My own differs in only one particular: I wouldn't bother shielding the coupling loop.Shielded or not, it is going to pick up exactly the same signal that is circulating in the resonated primary loop--which also includes exactly the same noise that the primary sees. No net benefit.
Secondly, the presence of a shield on the coupling makes it harder to maintain the balance of the primary windings to ground. A shield is going to have to be grounded somewhere (and preferably not via the coax all the way back to the receiver), meaning that it becomes more critical to keep it well centered within the primary winding. Otherwise, one side or the other of the primary will have more capacitive coupling to ground than the other, resulting in imbalance and reduced noise rejection. Most of the time it won't be a huge imbalance, but why risk it when there's no benefit to be had anyway.
Speaking of coupling to the main loop, there are a couple of additional options to consider other than a secondary loop. Remember that a resonant primary loop can be regarded as either series or parallel resonant, depending on how you prefer to sample its "contents."
Viewed across the capacitor, it's a high-Z parallel resonant LC circuit that yields a voltage you could amplify and then send to a receiver. There are balanced-input instrumentation circuits you could use, but I suspect the power supply needs would be hard to meet with sufficient common mode rejection in the real world with a remote loop.
Viewed in series with the capacitor, the L and C are series resonant and the circulating signal current can be sampled with a very low-Z transformer. Transformer coupling means the active circuitry itself need not be balanced, and that also eases the power situation. One turn passing through a toroid with a lot of secondary windings terminated in 50 Ω is one way. The Burhans loop preamp with the Xicon audio input transformer is another, although you have no control over the turns ratio and the series-R is therefore harder to control. Another possibility for transformer coupling might be the current sensing transformers used in SMPS-es, some of which are intended for 50 ohm termination and may work up to hundreds of kHz...but I haven't tried those yet myself, despite long-standing plans to do so.