Can I apply for a 5-year DTV visa from my home country while holding an ED visa and using a re-entry permit?

I am somewhat doubtful you have any ED VISA 😮

You sure you're not actually on an extension of stay (look at the stamp in your passport 😉 )

If you are indeed on an 'extension of stay' get a single re-entry permit right after you get the next extension, leave the country, and when you're back in your country apply for the DTV online thru the thai consulate there.

There won't be any problem with the current extension you're on. They only deny DTV applications when people still have a valid VISA in their passport and I believe you do not have a visa, and instead you have an extension w/re-entry permit. So no issue at all.

Apply for the DTV, if you get it print out the PDF give it and your passport to the officer at passport control when you stamp in and they'll stamp you in on that rather than the re-entry permit tied to the ED extension.

AND

if on the rare chance the DTV is denied (unlikely but possible) you could still come back and get stamped in until Apri 13th when your extension expires