Our Aerolite 174es clone of your Kodiak 172e came with a 3500 lb Lippert from the factory. A larger one wouldn't hurt, but I've found the 3500 to work well in this application. If you are buying for yourself, I'd go with a 4,000 or 4,500. The extra power doesn't hurt and you can take it with you if you upgrade to another unit that can benefit from the higher capacity. Get the largest you can afford but don't go below 3,500.