Just thought I should share our experiences with our solution for the dogs entering/exiting the van. We purchased the Pet Step II
and used it for the first time during our 5 night excursion over Thanksgiving.
Overall it worked great although it does take several times for the dogs to get comfortable with it. We store it between the gaucho and driver seat. It fits perfectly for us and has the added benefit of creating a barrier between the cockpit area of the van and the rest of it that the dogs can't cross. It is also light and very easy to setup. Finally, it is strong enough for us to use as a ramp in and out of the van.
The downsides to this solution is that you need to pull it out of the van anytime you want to set it up. Also, you cannot shut the side doors while it is deployed, even if it is rested on the nerf boards. That is not a big deal to us since it is so easy to setup (just unfold and put into position).
This is the best picture I currently have of it: