Is there a way to use the Mojolicious rendering engine to render a template outside of a web request?
yes
use Mojolicious::Renderer;
my $renderer = Mojolicious::Renderer->new;
push @{renderer->paths}, '/path/to/your/templates';
my $template = $renderer->get_data_template({
template => 'foo/bar',
format => 'html',
handler => 'epl'
});