I think it's 10,000 baht for a single traveler, on a tourist visa exemption and 20,000 baht for a family. You get stamped in for 30 days with a TVE. Your GF should consider having 10,000 baht (or the equivalent) cash in hand as she is eligible for a TVE.

With a valid tourist visa (30/60 day, single entry, double entry: obtained in another country), the requirement is for 20,000 baht for a single traveler.

"Visa Run" might lead to some confusion, but give it a try. Most tourists visit Thailand for tourism.

Not having the cash on hand required by law may lead to denial of entry. Not having a hotel reservation may also lead to denial of entry.

So it doesn't sound like much of a hassle? Just the one question, easily dealt with, in what 8+ entries?

DMK is generally acknowledged as being a bit more challenging for some travelers re: Immigration. BKK less so.