I can explain what was going on.
First off, Cousin Eddie is an idiot. He's uneducated country moron who doesn't think before he does stuff, and can't hold down a job, due to being stupid. He also has a lot of aspirations, but no business sense at all. He never bothers to figure out how to do things the right way. His wife, while sweet, isn't much smarter, and it's obvious she's content being a housewife while dad fails again and again at getting a steady job. There's a reason they are so poor, they live in an RV instead of a house (though in Vegas Vacation, they had a crappy house out in the desert).
Second, in a conversation Clark and his wife had, Eddie had been out of work for seven years. He had been holding out for management position, which shows you just how dumb he is. You don't get a management position at ANY job by just walking in and hoping for the best. I would be amazed if he could feed his family, never mind get them presents for Christmas, but then again, he seems more concerned about feeding the dog than he is feeding his kids. You saw how many big bags of dog food he grabbed at the store.
He was basically taking advantage of Clark's kind heart and mooching off of him. It's probably how he's survived all these years with his bad handling of money. Mooching off other people's charity. You heard how he shocked Clark by telling him they were leaving "next month," meaning he was going to have that hideous RV there, mooching off of Clark for a solid 30+ days.
Giving Cousin Eddie any money as a gift would be a waste. Chance are, he'd spend it as quickly as he could, or make a really bad investment within less than a month after leaving. He's one of those relatives you wish you were NOT related to.
3 years ago
And lets be honest, they probably weren't planning on leaving in a month either. They would stay there for as long as Clark and Ellen would allow. It's not like they had anywhere they needed to be. As long as no one said anything, they would stay. Clark and Ellen would have to ask them to leave before they would even consider it. And I'm sure Eddie would have some sob story and lay a guilt trip on them about why they needed to stay. It would eventually come down to Clark practically throwing them out.