When I first looked at your pictures I thought the retainer was installed backwards but when I looked in the manual it appears to be the same retainer and is installed the way that your picture shows. This is the third type of retainer that I've seen and all of them are different. Other that duplicating what it looks like when taking it apart how do you know for sure if the retainer goes over the nut or between the nut and the bearing washer. The cotter pin is a no question replacement but these multi-fin retainers don't all seem to be the same.
I've read several of the responses and the discussion around using EZ lube, packing the hub, or just packing the bearings have really been discussed for many years by many trailer owners/manufactures. My take and what I follow is the bearing must be thoroughly packed with high temp grease, the hub should be filled with extra grease, and recently I've been using the EZ lube just to add a little more grease after reassembling. I don't agree to only pack the bearings. The extra grease in the hub is actually helping to cool the bearing grease and I believe as the temperature increases it adds cooler grease to the bearing surfaces. I'm sure there are flaws in my thinking but I've seen what locked bearing will due to an axle so I want as much protection in the hub as I can get. One other thing about using the EZ lube is I purchase the higher quality double lipped seal (about twice as much as the standard ones) to help with the extra pressure but I am also using a had driven grease gun and rotating the tire slowly to allow the pressure to stabilize. All I'm saying this works for me and I like the results.