--a diagnosis of pure small fiber neuropathy would be unlikely; the usual presentation of small fiber neuropathy would not start in the thighs.

There'd more likely be symptoms in the furthest reaches of the extremities first, but if progressing, it would slowly "crawl" from the those extremities towards the center of the body.

Meralgia parasthetica cannot yet be ruled out--it's very hard to image the spaces through which the lateral femoral cutaneous nerve passes and may become compressed. But yes, there is also the possibility of one of the vascular autoimmune conditions that can have neuropathy as a symptom; these neuropathies are often patchier in distribution (sometimes referred to as a mononeuritis multiplex).

See:

Immune Neuropathies: Axonal