Camping Djing out of my car

I'm going camping soon and wanted to play some music.  My XDJ R1 user manual says it uses 28w, I have a couple LED rope lights that I'm not sure about, but probably don't use much power(all using an inverter), and I'm connecting a speaker to a 150 watt JL Audio monoblock car amp.

My Jeep has a 140 amp alternator, but I don't know how many amps it idles at, though.  I plan on leaving the jeep idling while playing music, do I need to worry about killing the battery or anything else?  How long will the battery last before I need to worry if the Alternator can't keep up?  I feel like I'd be fine with power to spare, but wanted to ask first.  Seems like every time I think an idea is OK I have 3 people telling me I'm going to kill something.

Thanks!

You will see about 14.5V when charging on a typical alternator. It is extremely unlikely to near impossible that you will run out of power whilst idling. If you are really worried just take a spare battery.

Don't bother with an inverter for the rope lights. Just buy some dirt cheap 12V LED strips and connect directly to battery.

Why not hook up a small solar panel to keep some charge going into the battery?

Maybe not but it'll still top up the battery during daylight hours.