What is the best way to tell the jury about the range of punishment for a second DWI without drawing an objection (at least not getting one sustained) for alluding to priors?

Per Oliva v. State (2017 Tex. App. LEXIS 2594, designated for publication), the prior is an element that you have to prove BARD, so you absolutely talk about it to the jury. You don't hide it at all.

The case is pending PDR, but both parties submitting briefs agree that it should be an element.

In light of Oliva, our county has decided to hold off on DWI 2nd trials until we get an authoritative answer from the CCA.