I did change the fork oil without removing them once. I used a little plastic syphon I got at Lowes that is made for filling laterns and heaters with fuel, it has the squeeze bulb for making it suck & blow

... costs about $6 +/- I think. It is not the best way but you can flush and fill both forks in about 30 minutes this way.
When I did mine I syphoned out the old stuff first (was hardly any of it in there ... so much for dealer prep on a new bike), then filled both tubes to the very top with fluid (cheap
Dexron), tried stirring it around a bit, then sucked it all out. Then I did it again. Then measured the exact amount the forks are supposed to have (Amsoil 20W by the way) and poured it in, put the caps back on and was ready to go.
Doing the fill/flush twice got most of the junky fluid out, little as it was. Like I said, it is not the best way but it is better than leaving bad stuff in there. It will be fine until you can do a proper job of it at a later date.
Regarding the 20W oil, I
REALLY like the feel of it. The forks actually feel like they are dampening something compared to before.