I think you might find it vastly easier to use a vacuum sealer with one hand than attempt to do the water immersion method of sealing a ziploc bag with one hand.
If you are in the US, foodsaver has a few less expensive models, like the V2244 that don't have any bells or whistles, but they do have a low profile design and a lever on the side to lock and unlock the vacuum & sealing bar, making them something that should be easy to operate with one hand.
The higher end ones are more complicated and kind of need to two hands to work.
You don't need to use their bags though. I buy bags from "commercial bargains" on amazon, it's not quite as thick, but they are 1/4 the price of foodsaver bags and I have had no more failures with them than I've had with foodsaver.