This is why I'd never own a vertical dropout tri/TT bike. Sorry that doesn't help the situation. But I wouldn't do what you have listed.
You could perhaps experiment with running wider wheels like an HED. 23's site shorter on those than narrower wheels. You'd just have to measure your chainstay width. If your rims are really narrow now, even the older HED "c2" width wheels might be wide enough to fit that 23 tire. Maybe find a local who owns a set of said wheels and meetup just to test fit.
Used HED's go for reasonable used prices if they aren't the newer 25mm wide ones. The 23mm wide ones go for pretty reasonable.