I did a search but couldn't find this one answered.

I have a double entry tourist visa, the first entry of which has been used. I am outside Thailand now and will be returning soon. It appears I will not be in Thailand for more than 30-days thus I would rather enter on a 30 exempt stamp then use the tourist visa on the following entry which will get me 3 months in the Kingdom. i.e. I would like to save the second entry of the tourist visa for the entry after the next one. Is it possible or must both entry's be used consecutively?

It is possible but current policy seems to be it may/most likely will not be allowed.

So what's my approach then? Just don't mention the visa and hope they don't notice it?

The would likely be the safe path - if you see them using you could then ask about not doing so and hope for the best.

I too would go with the stealth approach. If it does get used you can protect the stamp with a re-entry permit (1000 Baht) if you will be back in Thailand before the 60 days expires.

when you enter Thailand you can explain your situation to the officer , but final decision lies with the Official.

May be it helps if you have a itinary/ticket prepared that shows that you plan to leave within 30days and come back later on to stay a bit longer.

However please crosscheck the validity of your visa.

Well I went with the honest approach and asked. I was told, "If you have a visa you must use it."