Originally Posted by
jiejie
Yes of course it is possible but you need a LOT of time, and be willing to deal with the possibility of downmarket accommodations in outposts you had no intention of seeing, simply because of transport connections and border opening times.
Originally Posted by
jiejie
Laos inbound--usually you need in advance except at the Friendship Bridge crossing Nong Khai to Vientiane. Thailand inbound--most borders usually fine to get a visa-free entry stamp, but you only get 15 days.
Good to point out that entering Thailand by land will only give a 15 day visa exemption stamp. As for Laos the only border I'm aware of where a visa on arrival is not given is at the crossing on the Mekong from Cambodia. Things might have changed since my myriad crossings though.*
Here's my take:
Starting at Hanoi there are several possibilities. In the first take a bus direct to LP (1+ days) for another head west and cross into Laos near Dien Bien Phu. Continue down to LP from there (2+ days). From LP to Vientiane there are many buses and it should take about 10 hours. You can pick up an overnight sleeper bus to Pakse which is a long ride but allows you to spend some time in southern Laos on some Mekong islands or up on the Bolaven Plateau.
Cross into Cambodia on the Mekong and travel to Kratie where you should be able to get a bus to REP. Alternatively there might be transport from the border. After taking in the temples continue to BKK crossing through Poipet/Aranya Phratet.
You might need a Cambodia visa in advance, in fact even if you don't need one I'd advise you to get one. Also research about the prospect of an arrival visa for Laos.* I have previously been given a Cambodia visa from the Hanoi embassy. You shouldn't have problems assuming you have sufficient time.
*I have no experience crossing into Laos from Vietnam.