As I recall Malaysia requires 6 months of statements showing 500K every month, business registration of employers etc, accommodation booked in Thailand. FB posts detail rejections for not having docs notarized. You can apply again in the event of rejection and enter Thailand. Check with Penang before submitting your application as embassies change their rules regularly. It may be less demanding than before. Divya has given very good advice regarding Vietnam and Laos and freelance docs. Jakarta is a very good embassy to apply from also.
You could apply with a portfolio and some contracts and the 5O0k. Choose the right embassy to apply from though to increase your approval chances. Taipei, Malaysia will very likely want more than that. If you don't have payslips, you can show bank statements with your payment deposits.
If the property is part of your rental business, it will be an issue. If it is just for your living purposes, then should not be. The letter you need can be easily got on ChatGTP.