The general IATA rule regarding accessibility of Cargo Aircraft Only (CAO) shipments is that they will need to be loaded visibly and accessibly to the crew in flight, with the exceptions of Class 3 (Flammable Liquid) Packing Group III with no subsidiary risk, Class 6 (Toxic & Infectious Substances), Class 7 (Radioactives) and Class 9 (Miscellaneous DG). All other non-CAO shipments may, generally speaking, be loaded anywhere you please with the exception of RRY and MAG.
There may be operator variations filed by individual airlines prescribing stricter requirements, like for instance those of FedEX, but LCAG follows the general IATA rules to a very large extent. LCAG does have a few minor exceptions, which are all freely available in the IATA Dangerous Goods Manual.
IATA also allows for any and all CAO shipments to be loaded inaccessible in a Class C compartment. On the LCAG MD-11F the lower-decks (FWD and AFT) are both Class C, and they allow loading of CAO in those holds.
There are, of course, exceptions to these rules. If one is flying to the US, for instance, USG-13 comes into play, which basically says any ULD holding more than 25 kg or litres of DG must be loaded accessible, except for RCL and RNG where the limit is 75 kg or litres. The exception to this rule (there's always exceptions in DG world!) is if the DG is loaded on a pallet, and that pallet is accessible, then there's no limits to the quantity carried.
Want to learn more? Get on a full 5-day IATA DG Category 6 course. The Cat. 10 course which is mandatory for flight crew will only teach you so much, and we all know that a little knowledge can be a dangerous thing.