Gary,
What worked best for me was to have a train of sleds and the passenger road in one of those, sitting. My passengers sat on some of the stuff (buckets, bags, etc.). I stand in my sled and do not use a seat. The sled sold by Snowdog comes with a very strong steel ring around the sled itself, making it very strong where it connects to the Snowdog and the hitch point where the sleds behind it attach. The hitch at the front of the Snowdog has a shock absorber spring that smooths out the jerks of the ride between the engine and the sled train.
I purchased 3 additional inexpensive sleds (I believe they are made by Otter) and I didn’t feel the need for the wear runners or skates. They were all fairly cheap ($80 or so). They seem to work fine and I can easily replace them. The key for the other sleds is that they can stack or nest together (preferably on top of the Snowdow sled upside down on the dog itself) to minimize transport space. I would HIGHLY recommend a rigid hitch system between the sleds to keep them in place when you climb/descend hills and ramps. Without the rigid hitch, the trailing sleds will hit the sleds in front on the downhill. They also need to detach for transport. I found some inexpensive ones here:
Rigid Hitch System
Your wife may be able to simply sit on a bucket and hold the sled edges, or even sit on your flip-over, depending on how it is configured. Another option is if you got 2 of the more expensive Snowdog sleds for the front 2 of your train and use their seat, but it is probably not needed. I just bought a Clam X300 and am going to see if I can sit in one of the seat of that sled and drive the Snowdog. I think it might work for me.
Also, I added carbide studs to the track of my sled (very cheap) and that this was very helpful on the hardpack and ice, especially on the ramps. I put in KoldKutters with an electric drill:
Kold Kutter Carbide Studs
One more item, I bought the Standard Model, not the compact. I considered the compact, but from what I had heard and read, it was not as good a performer in the deep powder snow. I end up in deeper snow fairly often. Just one thought to consider. I think you will be pleased with either one.