I have a Quintrex Wanderer 320 with a 4.5 Yami motor. Both units a light and easy to load and unload and comfortable for two. Great for the rivers and dams, bit on the small side for Crock rivers.
A Rhino side loader fitted onto the canopy of the DMax and a Folda Trailer carried in the canopy, hook up the van and away I go.
If you are towing a van and want a rooftop tinnie, chances of you being within legal weight are very slim. As Peter says, well worth checking (with actual weighing, not just approximation). Last year Qld Police reported over 90% of vehicles they tested (in voluntary weigh stations) towing with a rooftop tinnie were overweight. A recent YouTube video by a mobile weighing company said 100% of the vehicles they checked were overweight!