What kind of QT container are you planning on putting him in? You can put him in a small container and float it in the regular tank but as you said, he may jump out a lot. If you can, try and get a 1g goldfish bowl or tank that is covered. If it is 1g, it will be easier to measure out the salt/medication. You will have to change at least 50% of the water every day but in a 1g, it will go by very fast. You can put the heater from his regular tank in there so he stays warm. Does your female have a heater in her 5g?
Everything else in your tank looks good. When he gets back in his regular 10g, you might want to try and keep the temperature stable at 78-80 degrees farenheit. Otherwise, good.