Hello and welcome to the forum, Claire.
I'm afraid I can't offer any advice on keeping larger tortoises but I am very envious of your land and having the space and time to be able to look into having some of your own.
There is someone on the forum who posts now and again and keeps Aldabras and Sulcatas. I think he's called Big Ted. You may want to look up some of his posts. There are lots of great photos.
Good luck with your research!
How many Marginated torts do you have? They have such stunning shells.
There are a few on the forum who also have Margies.
Anyway, welcome.