For Bangladesh I have heard of only one person travelling with a motorbike there and he had huge problems with customs etc. If I were you I would havw researched a good bit before entering that country on a foreign plated bike.

Myanmar - right now the border is closed - or you can only enter and exit at the same border crossing, something that makes overlanding impossible. Hopefully the authorities will sort it out and overlanding will be possible again. Although in these countries you never know...
The price of crossing Myanmar with guides and permits etc have been as low as 1000 USD including accomodation. Depending of the length of the crossing (how many days) and the number of participants in the overlanding group. The more participants - the lower price. Have a look at this Facebook-group: https://www.facebook.com/groups/152596798515738/

Thailand - overland crossing is possible but a lot of red tape is required. Most essential is s letter where the overlander explains his intention with visiting and travelling in Thailand, with itinerary and hotelbookings and the letter must be authorised by an embassy or consulate. Permits to travel through the country can only be handled by certain agencies - insurance is in the package - I think I saw the price 7000 baht all included. Which is around 200 USD/180 €.
The problem as I understand it is that going through Thailand twice as if youre coming from Myanmar and then going to Laos/Cambodia/Vietnam and then to Malaysia and Indonesia dont seem like an option. To get a aecond entey was said to be not likely to be an option. But there are much uncertainess to this the new rules and regualtions for foreign vehicles in Thailand are new and have not been enforced long.
Have a look at this Facebook-group:
https://www.facebook.com/groups/1024579897597702/

Laos - theres much uncertainess there as well. There seem to be a law that requires permits for foreign vehicles travelling in Laos that have not being enforced very strictly before - that now are being enforced very strictly. In the befinning it was only vehicles coming in into one province of Laos that were required permits but now it seems to be more provinses involved. But things are not clear for the moment. I do think travelling through Laos will be possible although some red tape will be required for sure. Check out the websites of Rideasia.net as they usually are the best source for updates.

Vietnam - permits needed in advance and are a bit expensive if I remember right. Dont know much about travelling in Vietnam though...

Malaysia and Indonesia - quite straight forward if you have a Carnet. Some papers needs to be done when entering Malaysia but nothing to worry about.

__________________
In the end everything will be fine. If its not fine its not the end....