  The homogeneous Bethe-Salpeter equation (BSE) of a (1/2)$^+$ bound system,
that has both fermionic and bosonic degrees of freedom, that we call a {\em
mock nucleon}, is studied in Minkowski space, in order to analyse the chiral
limit in covariant gauges. After adopting an interaction kernel built with a
one-particle exchange, the $\chi$-BSE is numerically solved by means of the
Nakanishi integral representation and light-front projection. Noteworthy, the
chiral limit induces a scale-invariance of the model and consequently generates
a wealth of striking features: i) it reduces the number of non trivial
Nakanishi weight functions to only one; ii) the form of the surviving weight
function has a factorized dependence on the two relevant variables, compact and
non-compact one; iii) the coupling constant becomes an explicit function of the
real exponent governing the power-law fall-off of the non trivial Nakanishi
weight function. The thorough investigation at large transverse-momentum of
light-front Bethe-Salpeter amplitudes, obtained with massive constituents,
provides a confirmation of the expected universal power-law fall-off, with
exponents predicted by our non-perturbative framework. Finally, one can shed
light on the exponents that govern the approach to the upper extremum of the
longitudinal-momentum fraction distribution function of the {\em mock nucleon},
when the coupling constant varies.
