@Mike ********
I think you will be fine with a multiple entries tourist visa now. Just be prepared to show onward and return tickets upon entry if they’ll ask you.
-Professional landborder company, yes that’s a border run with a company that prepares everything for you and make sure you’ll be able to return with them on a new 60 days visa exemption. (Price 3500 -5000 baht)
-Safe airport entry or prescan is a service at the airport where an agent prepare your entry and escort you through the immigration and make sure you’re allowed to enter on a new visa exemption. (Cost 7-8 000).
As said if you don’t have any excessive travel history beyond the 2,5 months my guess is that you’ll be fine with a multiple entries tourist visa for your planned stay now and might just risk to be told to get a proper long stay visa as a DTV if you plan or wish to do further long stay in Thailand.