You're on the right track about weight issues.
First thing I would recommend is load that VAN up with everything that would be in it for the camping trip.....driver, passengers, all the stuff on/under the seats and fuel.
Then go to a CAT Scales and get weighed.
Weigh ticket will show: Front axle weight, Rear axle weight and Total Van weight
(everybody stays in vehicle during weighing......cost $10)
Now with actual weight numbers you will have a better understanding of size/weight of trailer you can tow vs mfg. tow rating with an * or **
As for which trailer....no help there. Never went any where with that many kids except when I was one of them :B
Look at trailers GVWR and figure 12-15% of Gross for tongue weight.
Then look at your weight numbers...can VAN handle that tongue weight???
