I've done it on my lift, but tbh its do-able on the ground just the same. The challenge as you noticed is finding spring compressors that can fit in the space.
Something like this would be most suitable I think:
You need something which goes in from the side as otherwise the lower arm and / or the body is in the way. It helps if you drop the lower arm by taking the two inner bolts out, but that could get tricky on the ground as it's hard to get everything back together. You do need to compress the spring a lot to get it out because the upper platform is about 30mm thick.
Mine was sitting lopsided because the bottom coil broke off one spring. That one was easy to get out, but the other one did need the control arm loosening with the threaded bar type compressors I have.