Ya, I don't have a drain plug in any of my pans, but I really should. What I do is every 30K or 3 years or so, I drop the pan using the "Loosen them slowly from one end to the other until I have only 2 of them holding the pan". If for some reason I feel the need to change the fluid in between, I'll generally suck it out with a suckin' machine. I have an air operated one at work and a little 12 volt one I picked up from Amazon and that one stays in the barn on the farm. And then just refill without pulling the pan.
Sometimes it surprises me how resilient trannys can be. I got my 96 Grand Cherokee at 275K, the trans fluid was brown and there was a lot of not good looking stuff in the pan. Who knows when it had been last changed. Well I did the fluid and filter, sucked it and filled it a few times that week until the fluid stayed pink, and it's still going at 375K now.