REI fleece here as well for the “warmer” temps.I use REI fleece for water above 70F, not in the temps the OP mentioned. Brrr. I guess it depends on one's cold tolerance.
Base layer is muy importante. I like Smart Wool or Meriwool 250 thermal pants/shirt. I’ve used Coldproof and other fancy synthetic for base but the merino wool seems to work better. It also still insulates when it’s wet.
The DUI Duotherm 300 one piece undergarment should fit your temp range. I played around with mine in my pool when the water was 47°. I wasn’t toasty but I wasn’t cold. Like going for a walk in a shorts and t-shirt on a 55° sunny day. And that was with the Coldproof and not the wool baselayer, DUI advertises it for 45-65° waters. Would certainly be worth a look if you can find one on the used market.