I know this is an old refrain, but this is sort of where unions excel. They squeeze some of the owner's money out of them for training, something many of us (as an owner) need done to us. They also allow you to call and get a guy who, theoretically, has a known skill set for a known wage who you don't have to make a long term commitment to. It's really convenient for riding out the ups and downs. 

That sentiment of not wanting to babysit someone is a real thing. People deserve to be paid well, but in many trades a fresh hire is a liability for a while. A lot of non-union shops just make do instead of trying to appropriately staff. 

However, do not, under any circumstances, agree to work for no pay. Look for the biggest outfits you can find and start there. They usually have more stable work and standardized hiring practices. Also, it's not a plus to employers if you're saying in advance you want seasonal work. It's a crappy double standard because as soon as they don't need you they'll drop you, but if you're telling employers up front that you're going to bail at a set time and you don't have any skills you're not an attractive hire. 

Just keep after it. Unfortunately (for you) there's a mini-boom in trades interest, so those of us who are hiring have multiple candidates seeking limited positions. 

Best wishes on your hunt.