Both of those should be pretty effective, however, as was suggested on SMTnet it doesn't hurt to test it out. If you see sag you don't like you can experiment with carriers or simple support structures. I have a v-scored 280*110mm 2up panel here (odd choice of alignment edge but there go) I did try it just for fun the wide way round and that of course dipped quote bit on the score, but it didn't break. When I visited other sites to see new Ovens, one place insisted on making panels to their std size, to keep their profile super reliably consistent. That was a pretty large panel somewhere around A3 size, however that Oven was the one I chose and as standard comes with both mesh and pins so we have that fallback option should we need to. So far however I only use the mesh for awkwardly shaped low volume boards or when the pin chain is busy with a different size. I would say perhaps that more than 2 boards across when using v-score probably not ideal but otherwise I think your panels are basically tiny.