congrats on getting the wags going again
4-5mm isn't alot of thread for the nuts to be holding on to with your spacers ... clean the inside of the rim and the face of the spacer, wack a bit silastic evenly onto the surfaces and stick 'em together, bolt the wheel back on nice and tight and leave it sit for a day. Shouldn't have the spacers move after that.
but first - go visit your local nissan dealer and buy some longer wheel studs .... cant remember which one but a skyline came out with some about 7-10mm than the 1200 ones