Q:

Do virtual mesons exchanged between nucleons in the nuclear force ever decay before reaching the recipient nucleon?

So my understanding of the nuclear force so far is this (please correct anything I have wrong):
Being a residual of the strong force, the nuclear force is mediated (in part) by the emission of virtual gluons by quarks, not completely dissimilar to the exchange of virtual photons between electrically charged particles that mediates the electromagnetic force. However, unlike the strength of the electric field between two electrically charged particles, the strength of the gluon field between two color charged particles is constant as a function of the distance between them. This is due to the so-called "flux tubes" that are formed. My first attempt at wrapping my head around these has left me scarred and deformed, but I think the concept is that they effectively behave as strings and exhibit a tension force.
As a result of the energy requirement of maintaining the flux tube increasing linearly with distance ( ΔE = W = F ⋅ d ), it would be more energetically favorable for a gluon emitted by a quark confined within one nucleon to a quark confined within another nucleon to decay into a meson. [Perhaps this has something to do with the principle of least action?]
One of the more common (I think?) decay products of gluons involved in the nuclear force is the neutral pion π0. Neutral pions usually decay into gamma rays, which I'm assuming would be observable to some degree. This leads me to believe that virtual mesons never decay. Is this true? If so, then how so? Something something uncertainty principle?

A:

for a gluon emitted by a quark confined within one nucleon to a quark confined within another nucleon to decay into a meson.

The strong nuclear force, i.e. what keeps the nucleons within a nucleus,  is modeled with pion  and rho exchanges between nucleons, color neutral quark antiquark pairs. So a gluon is never emitted by a quark into another nucleon because of color neutrality at the distance of fermi that enclosed the nucleons in a nucleus.
If one wants in a nuclear model to use gluons, one has to take care of color neutrality.
The whole interactions that keep the nucleus together are modeled with the pions and rhos and ... off mass shell, i.e. virtual particles. Virtual particles have the quantum numbers of their name, but are  off mass shell, i.e. their mass varies under the integration which will give the final crossection. Thus the neutral mesons exchanged cannot decay, because they are not real.
The gluons do not decay, they are part of the elementary point particles of the standard model.

