Just wanted to share a simple build. I purchased the Rock-N-Roller cart a few months ago and have been very happy with. It helped with cutting down the trips from my truck to the venue.
i almost purchased the Rock N roller table attachment they make:

but i will only need half and it is too narrow for what i want to use it for. i also felt it was a bit over priced.
so just made a simple solution for my own table:


I used used a couple of slotted angles (1-1/2" x 36") from Home depot at around $8 each . about 5 dollars worth of bolts(m8), lockwashers, and fly nuts. And some scrap plywood 24" x 34"
cut the angles like this at the ends (sorry i forgot to take a photo). i just used a jigsaw with a steel bit.

attached the ends like this:

Just bolt on the plywood to the slotted rods using flat head bolts and countersinking the plywood.

I just have to add a skirt and carpet, paint, or laminate. havent decided yet.
It is quite strong for what i needed. It may be wobbly after you attach the rods, but if you shorten the base it will tighten and the wobble will go away. watch this video on this guys custom table and how he stopped the wobble:
https://youtu.be/nOhxc21i-b0?t=3m36s
i am thinking, if you have a light DJ coffin or a thicker gauge angle rod you can leave it without the wood table and just place the coffin on top of the rods. but havent thought of a way to avoid it from slipping off. maybe the weight is enough? ill test it and report back. its already quite strong for what i need and very light to carry around.
currently the price for the Rock N Roller brand tale attachemnt is at 49.99 on amazon which is not bad. but the specs are not what i want and ill end up modding it anyways with a different table top.