Just get a 60 day single entry tourist visa then extend for 30 days once shes in thailand. Simple process. The only issue being youll need to show a ticket at check in to show youre leaving thailand within 60 days so just buy a cheap Air Asia Flight to Kuala Lumpar and bin it
The only questions will be that you have to transfer the money to buy from your own country so that will be known to your bank in your own country. That may raise questions but dont know
all my monthly bank statements are always 2 or 3 pages. If youre renting they ask for proof of accomodation. If you own the home, they ask for tabian baan etc