Lil
Bigfoot has a rubber torsion
axle. The answer depends partly on whether the
axle is welded or bolted.
The original
axle is welded, so it would have to be cut off and a new axle installed with a greater down angle in the axle arms. The Lil
Bigfoot has an unusual angled frame design, so some frame modification will be needed to mount a new axle. Cost $$$
If it's a bolted-on replacement axle, you could probably modify the axle mounting bracket to raise the trailer. That will not raise the axle tube, though, only the coach. Cost $-$$
Either way, some custom welding and fabrication on the frame is required. There is no simple bolt-on solution.
As to necessary, I've never been to the Baja peninsula, but I have taken our
Scamp, which is probably even lower than your Lil Bigfoot, on some rough back roads a couple of times. With careful driving, nothing bad happened. The trick is taking dips and humps at an angle. The most vulnerable spot is the tongue jack, and you can replace that with a swing-away jack on the side or this adjustable jack:
Ultimate Jack