The problem with putting a tongue box on the small trailer is that it needs to be right up against the trailer and as such it may need to also hold your propane
tank &/or your battery
(unless you move that to the rear) other wise you will find you have troubles with making tight turns with things coming to close to the rear of your tug. I once saw a Trillium
with a medium sized tote with a hinged lid on it used as a tongue box right up against the front of the trailer. Seem to recall that he drilled holes in the bottom and secured it with clamps to the tongue & his propane
tank was inside the box. As a result of the tongue box issue some people have put bumper mounted cargo racks
on the back of the trailer for putting bulky items such as coolers etc.... but then you really need to add weight
to the front of the trailer to compensate for that. etrailers.com
has a number of bumper type carries but they all need a receiver hitch at the back to work - but I know they have a Canadian warehouse. Canadian Tire
also carries one made by Sportsrack.
I found on the occasions when I have taken a large gang (2 adults, 2 kids and 2 big dogs) on a trip that using smallish square tote boxes (think they are only 18 X 18) for each persons clothing and shoes etc, another for all the dogs stuff etc, worked best as they stacked well on the floor of the trailer - much easier to deal with than bulky luggage bags etc. As the boxes have tight fitting lids it wasnt a problem to stick them under the trailer once at destination to get them out of the way.
Edit to add that Princess Auto also sells a tongue box
Have a great trip! I am sure your family will still be talking about it in the years to come.