I don't know if this would appeal to you, but...

You may want to try an Aqua Jogger. It is a floatation bely you wear in the water that allows you to remain upright in the water. You can then move your arms and legs (with or without weights) in a jogging or cross country skiing motion. The resistance from the water is great and it is a good workout.

Any large sporting good store should be able to get you set up, and the cost was reasonable (about $30 US)
Stephen