Split snake is best but you'll need your own preamps and a channel for everything.
You can also tap out of FOH channels with the direct outs. Since these are post-trim, you're now at the mercy of the FOH engineer's trim skills. If his channel is clipping, you'll get the noise too. If no direct outs are available, halfway into the inserts might work. Any further and FOH loses the signal so don't mess with them during the show. And too bad if they are using an insert for compression or whatever. Maybe there's a free aux send to tap that channel.
If you are rather limited on input tracks and get along with people, you could ask the FOH guy to group something (preferably instruments not played at the same time) and you could take that group out to one channel of your multitrack. Of course you can't post-mix the elements in this group if they are on top of each other. You're stuck with what the FOH guy did live.
With the AW16G you could arrive with one end of an 8-channel trs snake already in it.
Then you'd just need to tap the FOH console and fire up the recorder. Shouldn't take long at all.
With 8 channels - kick, snare, other drum, guitar, bass, vocal, and two left for another instrument or vocal, stereo oh/guitar, ambience, etc. Whatever the case.
If you're not interested in post-mixing then you could just take a "program out" of FOH and use a condensor or two in the room to capture crowd/ambience. You could use 4 inputs and mix it live in stereo or 4 tracks and mix it later.
Lastly, you could just take what the condensors give you (like a high-quality bootleg)