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PDX - Portland?
When I did my OW in central Calif in April, we did our pool sessions in a 82 degree heated pool. We did it in 7 mm wetsuits so that we were used to our weighting, buoyancy and the feeling of having that thick of a wetsuit on before we went out to the less forgiving ocean environment. We didn't wear hoods during training but were encouraged to at least put them on once to experience the feeling because hoods can freak a number of people out. Nobody overheated, you just let water in at the neck if you got warm.
By the time we went in the 55 degree ocean water, we didn't really have to worry much about our weighting or how to move in those things. We could concentrate fully on our skills and enjoying the sites!
A suggestion - if you do go to someplace warm to get certified, after certifying and getting comfortable, see if they have any 7mm wetsuits you can try diving with. If you go to Florida some shops will have them, I know the shop I use does. That way you can get comfortable and weighting situated before actually going into colder water. You shouldn't overheat as it would be the same as going into a pool with it....if you do find yourself become warm just let water in to cool off a bit.