I can handle the CLI installation but it's a bit tedious. Would the system be identical if I just used the graphical installer on the LXDE ISO and then removed LXDE with pacman and install i3-gaps?
yes, any two parabola systems are essentially identical, if
they have exactly the same packages installed - LXDE is simple
to remove; but it is also very small and non-intrusive - i
recommend keeping LXDE installed always, as a backup plan in case
something goes wrong with your every-day WM/DE