For those who may see the apeal of this method, perhaps some of the main dangers ought to be outlined, so accidents may be avoided.
As Dmattox has observed, there is a need for an elevating work platform; for many reasons, ladders often just aren't enough.
First of all, those forks are very slippery. A large number of accidents involve either the person slipping from the forks, or the platform slipping. This is why commercial platforms have chains, or some other means, to attach the platform to the forks.
Since the forks are also tapered, a C-clamp is not a very good solution, and WILL come loose.
Wood pallets are often made of very poor lumber, and are prone to breaking. They simply are not reliable enough to use this way.
As the forks are raised and lowered, or as the forklift positions itself, you really want to hold on to something. Without there being a railing, you often end up holding on to the forklift itself- in a place that can hurt you. It is not unusual for the chains of the lift to shift on their sprockets, which can easily remove a few fingers.
Again, commercial cages address this by having a screen on the side toward the fork "tower."
A final feature, one that has prooven it's utility, is a "toe plate," or 4" barrier, around the perimeter of the cage. This, apart from giving your feet warning that they're near the edge, is also good at keeping parts from rolling off.
Painting the cage a contrasting color will help the operator position the cage