When buying the XL, the only thing that happens is that you get more space on the right side. Everything in your garden will stay unchanged, although it may be a bit off-centered after the purchase
Think I should go for the XL or splurge on more stuff first? My garden in profile
That's up to you. I went for it as early as possible just to get it out of the way, but that's just me.
It'll look like this if you get it right now:
And like this if you look at the whole thing:
The trees and clouds will go all the way right, I just didn't feel like simulating it.
Edit: Just in case anyone else gets confused, this is @マット's garden where I've messed with the code (CSS) a bit to give a preview of what it would looks like with the XL expansion. I now realise that might not have been clear enough :D