I agree, most figs in 1:35 scale would work fine for a 1:32 dio. I'm not really sure about vehicles though, as a 10% discrepancy would be noticeable. But as Scorn said, depending on how you chose to orient your dio, you could make it work. Try posting in the dio forum, I'm sure people there will have other suggestions.
There are a number of kits of jeeps in 1:35 scale. Also, the number of accessories available in 1:35 is a VERY large list, and that could allways be used to fill up space as well..