After 90 days in Thailand, I have to leave the Chiang Kong border and go to Laos... it seems that you have to go back to Thai customs after two days (48 hours) at least, to be able to return to Thailand.. Is all this true...?

So, I've other doubt about my next trip to SEA. It's not specifically visa related, but a "show me the money" issue at the border :D

If traveling around SEA, after some time in Lao and Cambodia, the plan is to come back to Thailand, spend just a few days (3-5) in the beach and then fly back home. As that will be at the very end of our trip, we won't carry 500€ in cash (we'd spent it by that time! :D)

In that scenery, should I show 20.000baths in cash when entering Tailand under visa exemption? what about under a SETV?

Is it mandatory to show cash, or can I show a bank receipt or inform with (more than) enough funds?

Is there any difference regarding the proof of funds when entering by plane or by land border?

My main concern is: OK, I can withdraw enough cash from an ATM at, i.e. Siem Reap, just before go to Thailand. But... what I need is THB or US$, so, how can I get THB or US$ while in Cambodia, if it's mandatory to show cash in the border? Can I just walk into a cambodian bank and get US$ over the counter?

If I need to show the cash, it's not a problem at all, it's not a matter of having money, but of have to carry so much cash - I wouldn't like to travel around SEA with 1.000€ in cash, just to be able to show 500€ when entering Thailand just for a few days...