DONALD - I had figured up the price for the steel to make a similar trailer to this Pronovost and by the time I bought a cylinder, wheels/tires, & spindles I would have had as much or more $$$ in materials as what I paid for this used trailer, and it wouldn't have been as nice. SON & I pulled ALL the sides off a month ago in about 5 minutes to move a 4 ft x 5 ft x 6 in concrete slab on it as a flatbed. Took about 8 to ten minutes to reinstall them again. Think eight bolts, all 3/8" x 2" is what holds the sides on and together.
Story I was told, guy had some sort of HONDA garden tractor with ALL the attachments, including this trailer, and three winters ago when we had 120+ inches of snow he got tired of freezing to death and getting covered with snow from the snow blower so traded for a little Kubota FWA with a cab, heater & A/C, loader, etc. and this cart sat at the dealer for 6+ months. I got it at the dealers going-out-of-business sale for 60% of their asking price. I have NO idea where the guy got this trailer or what it cost.
ALSO, I got in the habit of pulling a battery cable off some of my CC's since I have to do that on my FARMALL's, they both have 12V alternator conversions and don't have the diode installed to stop the current drain from the battery when the tractor isn't running. Alternators have to have a little current to excite the fields I think it is, or they will never charge.
I've also noticed my batteries all seem to last several years longer since I've been doing this.
When I was still planning on building my own dump cart I looked for 2 or 3-stage hyd. cylinders like really BIG dump trucks normally have, They're perfect for the job, but I wanted something maybe 2-3 feet long that would extend out 5-6 feet. I heard someone say the leveling cylinders on "hillside combines" used to harvest wheat out west had cylinders like that. I lurked & searched the Internet and NOTHING, I did find a couple places that would make custom cylinders like that, for over $1000 US.
Since you have a single tube for the hitch on your cart, you might be able to install two smaller diameter cylinders that mount on the bottom down below that tube and gain some angle to raise your cart easier if you're not satisfied, or just add another cylinder the same size as the one you have. You can just "TEE" the lines from your couplers to the cylinders since they will share the load.