wetsuit vest for winter

Hey everyone, been a long time. I haven't surfed as much the past three years, but would like to go back to year-round in the cold North Atlantic if possible.
I have a 5mm Excel wetsuit and a bibbed hood, but it's not enough from January to mid April. Ideally I would get a 6mm wetsuit which has worked well for me in the past, but the prices are just crazy. I was thinking to supplement my wetsuit with a hooded vest worn under. I don't plan to surf when it's very cold outside, but maybe sneak in a sesh or two when the air temps are above freezing in mid-winter.
My main concern is retaining flexibility, my 5mm wetsuit already feels a bit constricting, but I hope to lose some weight before winter
I have a 5mm Excel wetsuit and a bibbed hood, but it's not enough from January to mid April. Ideally I would get a 6mm wetsuit which has worked well for me in the past, but the prices are just crazy. I was thinking to supplement my wetsuit with a hooded vest worn under. I don't plan to surf when it's very cold outside, but maybe sneak in a sesh or two when the air temps are above freezing in mid-winter.
My main concern is retaining flexibility, my 5mm wetsuit already feels a bit constricting, but I hope to lose some weight before winter
