By definition a thought experiment is a rigorous exploration of the predictions of a physical theory. You lack rigor and so there is not enough thought in your thought experiment for it to merit that description. You have ignored relativity of simultaneity and therefore ignored basic characteristic of special relativity, dating back to Einstein's original 1905 paper.
Let f,g,h be time-like inertial world lines. Let j, k be space-like straight lines. Let ℓ be a light-like straight line. Then we have in both coordinate system the following descriptions of these lines:
$$
\begin{array}{c|c|c} \textrm{Line} & \textrm{Frame} \; \Sigma & \textrm{Frame} \; \Sigma' \\ \hline \\ f & x = 0 & x' = -vt' \\ g & x = vt & x' = 0 \\ h & x = vt - \frac{d'}{c} v \sqrt{1 - \frac{v^2}{c^2}} & x' = - \frac{d'}{c} v \\ j & t = \frac{d'}{c} \sqrt{1 - \frac{v^2}{c^2}} & x' = - \frac{c^2}{v} \left( t' - \frac{d'}{c} \left(1 - \frac{v^2}{c^2} \right) \right) \\ k & x = \frac{c^2}{v} \left( t - \frac{d'}{c} \sqrt{1 - \frac{v^2}{c^2} } \right) & t' = \frac{d'}{c} \\ \ell & x = ct & x' = ct' \end{\array} $$ $$
\begin{array}{c|c|c} \textrm{Event} & \textrm{Frame} \; \Sigma & \textrm{Frame} \; \Sigma' \\ \hline \\ O=f \cap g \cap \ell & \left( x=0, \; t=0\right) & \left(x'=0, \; t'=0 \right) \\ P = f \cap h \cap j \cap k & \left( x = 0, \; t = \frac{d'}{c} \sqrt{1 - \frac{v^2}{c^2}} \right) & \left( x' = - \frac{d'}{c} v, \; t' = \frac{d'}{c} \right) \\ Q = j \cap \ell & \left( x = d' \, \sqrt{1 - \frac{v^2}{c^2}}, \; t = \frac{d'}{c} \sqrt{1 - \frac{v^2}{c^2}} \right) & \left( x' = d' \, \left(1 - \frac{v}{c} \right) , \; t' = \frac{d'}{c} \left(1 - \frac{v}{c} \right) \right) \\ R = k \cap \ell & \left( x = \frac{c d' \sqrt{1 - \frac{v^2}{c^2}}}{c - v}, \; t = \frac{d' \sqrt{1 - \frac{v^2}{c^2}}}{c - v} \right) &\left( x' = d' , \; t' = \frac{d'}{c} \right) \end{\array}$$
So by ignoring relativity of simultaneity, you improperly confuse lines j and k and therefore confuse events Q and R.
Imagine that. Somebody ignoring relativity of simultaneity in this science forum. As big as the 'holiday was' he still improved on presentation.