RCTgo

Hi folks,

It's been years since I've touched this game but recently I felt like returning to it as I'm older now and wanted to create my dream theme park.
I always play in sandbox mode because I can't be bothered managing finances.
So I started my park but soon realized I'm running out of space as sandbox is only 128x128.

I was wondering, is there a way to either: 
Edit my current sandbox save to increase land size? 
I've tried copying my park from the parks folder into scenario folder and then going in-game to edit the scenario (which is a savegame of my park) but there's no options to click in the right-hand side of the screen to manage landsize for example as there would be when starting a new custom scenario. 

Basically, what I am trying to figure out is how can I load my sandbox park in scenario editor and increase owned land and then saving to continue playing my park without having to start all over? Because as soon as I open my park in scenario edtior, the options to increase owned landsize aren't there like there is with a brand new scenario. 

Or: 
Can make a whole new scenario, increase the landsize to full and then use that savegame but copy my previous park all the way into it? As I really don't want to start building everything all over again. And sure, I could make screenshots and build everything the exact same but I that'd be a LOT of effort. 

Basically what I've tried is:
1. Copy my sandbox park from documents (.dat and .bak file)
2. Paste them in the scenario folder
3. Open the scenario editor and load up my sandbox park
4. I'm stuck. I can't increase owned landsize now. 

What am I doing wrong? Or is it simply impossible what I am trying to do achieve?

Thanks in advance.