One major postive about the trailer in your link is that its has exceptionally wide bunks which should greatly reduce stress and abrasion of the fabric.
The trailer does look to be fairly short for that length of boat and if driven like shown in the picture would place huge stress on the transom. Assuming the trailer were longer, you could probably fabricate a removable skeg support that would slide in place like a receiver hitch for transport and be pulled off prior to launch.
So far I've only owned 3 boat trailers, (all have been steel framed) so I don't have any experience with the point that John Y brought up about aluminum trailers being susceptible to currents. It's definitely something to consider if you will be launching on rivers or good sized lakes that tend to get windy. Hopefully some of the aluminum trailer users can give their perspective on this.
The last thing that strikes me about that trailer is the tiny tires. I can't imagine that they would be safe on the highway and they'd get stuck on every little rut on forestry roads. I would look for a fairly common sized trailer tire so that you could easily replace it from just about anywhere.
I've destroyed several cheap Princess Auto bought trailer tires (Carlisle, Lodestar etc...). Currently I have Goodyear's HMG2020 bias 205x14 8 ply which they make for U Haul trailers. They have been tough as nails and haven't even had a flat with them. If you can find a pair grab them (just not off someone's U Haul trailer
Depending on how much time vs money you are willing to spend, you could probably buy a sturdy used conventional steel framed boat trailer of similar length for less than half the price and make your own bunks for it.