From 2012 till 2018 I lived in Thailand with my Thai Wife and I used a retirement visa. I am english but I have property in Ireland and in July 2018 I emigrated to ireland with my thai wife but we have now returned to Thailand. We might be here for 3/4/5/6/7 months depending on when my irish properties become vacant. I entered Thailand on the 30 exemption and already have a visa run to vietnam booked... my question is " what should I do to maintain my legal status in Thailand"

You can get a 60 day extension on every entry as married to a Thai. 

Second option is to get/convert to a non-immigrant O visa and apply for a 1year extension with 400.000 baht in the bank or 40.000 baht / month income. 

 

If you don't have the funds, Savannahket issues a 1year multiple entry visa based on marriage without funds. 

Savan consulate 1yr multi be your best bet I expect,

60 day extension on your 30 day visa exempt and repeat that not bad easy option but if likely stay well over 6 months the type o multi entry be safest bet .