What is the best way to handle visa extensions and proof of onward travel while in Thailand?

Hi all I will have been here in Bangkok 153 days in 2 weeks when my 30 day visa extension expires, instead of my original plans of 60 days due to my Thai friend sadly being diagnosed with cancer while I have been here and she naturally needs my help,

I came into Thailand with a 60 day tourist visa then extended that by 30 days, then flew to Singapore stayed a week came back to Thialand got a 30 day visa exempt stamp that I also extended by 30 days, soon my time runs out again so I have booked a hotel in Kuala Lumpur for 10 days but have not booked a flight yet,

I'm getting worried now what would be the best way to return to Bangkok after reading others problems, I thought best play it safe and get a single entry tourest visa 60 days this time but that will last until middle of the Christmas Holidays which is an expensive and inconvenient time to travel out of the country and back, ideally I would like to extend that by 30 days also,

my main worry is I understand in KL they may ask me for proof of flight out of Thailand, I don't mind booking a flight if that gives me the best chance of getting a visa though,

my question is can I give them a departure flight date that is 90 days away taking in account of the 30 day extension I'm hoping to get on my Visa I will get from Kuala Lumpur,

Would this be accepted or does the flight date have to be within the time limit of the visa they are providing and not including any extention I may get after,

What are the chances of them asking me for flight information taking into account my stamps and visa history in my new passport, my old passport does show my travel to Thailand over a 5 year period but after each tourist visa I always returned to the UK for a few months,

I also carry medical proof of my Thai friends need for help, if this could be of help, I'm also 55 and retired, don't look like a candidate to work in Thailand,

Sorry bit long winded but I wanted to explain what visa and stamps I allready have,

Thank you for any help in advance Mike