I am very new at this too. I didn't know anything about the Puck until I became a owner, or till the night before when I did a bit of web surfing.
I think you should be able to pull one easy enough. The very early ones were 300 kilos/660 lbs. Mid 60's to sometime after my 71 they were a bit bigger and 350 kilos/770 lbs. I think this is the most common group. Andrew was kind enough to post the following link that explaned a lot:
http://www.oldiecaravan.de/Hersteller_A_-_Z/Eriba/eriba.html
I am not teribbly observant and even though the cabinets were out I missed a number of things. If you find one there are a few problem areas I have found on mine. The paint was missing on the top and pop up section. The UV erosion of the resin of the fiberglass did some damage to the top but just about destroyed the pop up section. I have a big challenge to rebuilt that part. Getting the edge right is a pain. Mine had leaks around the front window. There was the white powdery corrosion near the center screw strip below the window. If you see the skin corroded through near the screw strip you are going to find more under the strip. If you have to take it apart to fix it the skin would likely have to be replaced. For a quick fix to get by try sealing it with something. It will go down hill if you try pulling the skin loose.
Mine seemed to have had a few leaks. If the aluminum skin has been wet where it touches the steel frame you will find more corrosion there. Mine also had the steel frame rusted through around the front window, the bottom of the entrance and back bottom corners. Doing a permanent repair to any of those areas required lifting the skin and after corrosion had started it just crumbles away.
Mine may be the unusual but it is the only one I know. Hopefully not many are as bad as mine. I think it was left neglected outside for mother nature to give her best shot. If I had known it was that bad I think I would have passed it up. Now that I am working on it the work hasn't been that bad but I am going to be busy for a while. It is reparable and will live to camp again looking many years younger.
I don't want to scare you away. If you find one look it over good for leaks or corrosion then make a better educated decision then I did. It is the only rig I know of that is extremely light and nicely roomy. They have a reputation for towing well and long life. You could do worse.
Jerry