Clean transference of NonImmB and WP between employers w/o leaving country to get new NonB

Happy holidays and what better way to start the new year than to ask a question about a new Non Imm B visa.  I am quite familiar with the rule that once you quit or end a contract you got 24 hours to skedaddle (or pay 1900B for a one week extortion). not a typo

The school I taught with (and still technically on paper/contract) is on winter break and I am on very good terms with management. I informed the head of the school before we went on winter break (Dec 19) that I would not be coming back to teach when the term begins the second week of January.  

They told me I was a good boy and good employee so HR didn't need to know right away.   Delaying a Change Wattana date until I tell them "officially" then the loathsome HR/farang correspondent and I can make the trip to cancel my papers which would therefore set me scrambling out of the country (or paying a one week extension of stay).....COULD THIS BE AVOIDED?

Ethically, I worked part-time at another university(not my WP/Non ImmB sponsor) who were in need of emergency replacement.......ethically, meaning both employers knew what I was doing.

This uni (which should hold clout as it's seen as the number 1 if not 2 top public uni) will be starting school very soon.  However, they don't want my one year contract to start until February 1.    Other factor is I just came back today after going to Europe for Christmas and did not opt for the 90 day extension so now I am on 30 day extension.......didn't want to bother with paying the money or risking missing time to catch the flight which happened when I went to India last summer.......

If anyone has experienced switching from one job to another ie Non Imm B to Non Imm B without having to leave the country to get a new one (in my past it's always a trip to Vientianne).    

Would be great to hear your story or if you're in the know and can drop some advice that'd be much appreciated!

Thanks a million,

Mangy

PS.  Not trying to say I deserve special treatment but I am blessed enough to get a job at what most would say is the number 1 public university.........do you think this could grease the wheels?

Happy 2020