Martin, Thanks for this info. I am very new to this aspect (actually new to most) of photography. I have available the 18-55mm 3.5-5.6 VR II lens on the D5300, so if I try this I guess I will use the 18mm end of the lens set to f3.5 and ISO1600. I am in a pretty isolated area with not much light pollution so I could probably go 30 seconds, easily. The cable release and 100 shot limit is where I am a little bit confused. I do have a wireless control, ML-3 (I think that's the designation). I think I can use interval shooting with the D5300. I have not tried it, but I think it can be programmed to start at a specific time and fire every XX seconds, minutes, etc. This would probably be how I would set things up with the interval of a shot every 31 seconds using shutter speed of 30 seconds. Would the 1 second delay cause any problem? Or if using the wireless remote, just fire at 31 second or so intervals using it.
By-the-way, other than the problem of an almost full moon to wash out things, they are predicting fairly clear skys in my area.