I think this would be fun:

Whenever you have bitpack ideas, but you cannot/donot want to host a battle now, you can write an entry into your account's personal bitpack pool

Then when you are ready to host, you can check a button saying [randomly select bitpack from pool]. Thus the hostist will not know the bitpack till the start of the battle just as everyone else. And the bitpack will then be removed from your pool, so you donot host the same ones multiple times.

Each bitpack in your pool would be associated with a format, or even a list of acceptable formats. For example a bitpack such as:
"Make a song with alternating odd time signatures"
you would specify that this bitpack would be acceptable for all audio formats, so whether you want to host allgear, nsf or s3xmodit, this will be available in the pool. And if you host visuall or draw, it will not be chosen.

And a bitpack containing a .it file with samples would be specified as being acceptable for only s3xmodit (and maybe mptm too) and would only be randomly chosen if you are hosting a s3xmodit battle

Also, if none of the bitpacks in your pool match the format you want to host, then the option to randomly choose would be grayed out.

Just would be a fun option to surprise the hostist too, regular bitpack entry would still be available of course. thank you for your consideration!

Why not just save the bitpacks on your computer with random gibberish filenames that you'll quickly forget?