4 , 24x30 patio sidewalk slabs. They cost 5.00 bucks each and you put a chain and padlock on each end for front and back wheel. Its almost impossible to lift a bike with a 24x30 patio stone hanging on both ends, requires cutting two chains/locks, and sitting concrete on concrete means no rust for the building to deal with, no drilling into structural concrete and the whole deal can be disassembled and loaded into a trunk when you move. If it sat in front of your car it not a trip hazard and if you really wanted to , squeeze out some PL400 construction adhesive before you placed the slab down and you'll need dynamite to move it.
go to a marine store and buy a stainless u bolt, countersink the nuts on the back of the patio stone so it sits flat and fill the countersink with silicone/construction adhesive/gum what ever , so digging out the nuts is impossible with a motorcycle sitting on top. Its a $25 detterant and its that simple. Thieves want in and out, not cutters/grinders/ noise. Nothing is truly theft proof, but making it harder will really help.