I was once daft enough to say that my bike had had its stock plastic fuel tank replaced with a steel one. They wanted another thousand quid!
Make/use an A frame (engine hoist) to tie up subframe when removing rear swinger or put car jack/block of something under engine. Simples. Some bike lift stands like ABBA etc can lift whole bike up too.
I used a trolley jack and had the son hold it while I pulled the swingarm out and dropped in the other one