You might be able to do it if you have legit (non-cheat) single player experience, but the lack of checkpoints combined with only having a single life means each mission could take several tries (especially if you want to do the secondary objectives). Otherwise yeah it might prove too difficult since you have to be really cautious. There are youtube videos out there of people soloing the missions, maybe those could help.
There's no real reason to solo it though. Even if you can't get a group together, just set up a lobby with your controllers signed in and randoms are bound to pop in. Every extra body helps, even without communication.
And for the record you can do co-op with only one person/profile in the lobby (like any other online gamemode), but if you've got extra controllers you should use them.
Last edited by Veedrock; 05-07-2012 at 01:36 PM.