Ubass neck question

[Bass.swimmer]

Hello everyone! I have a question about a build I'm working on.

I'm currently making a ubass (18"scale length, quartersawn mahogany neck/back/sides). I was wondering, if I wanted to put "steel" strings on it (they're nylon core/silver wound), how screwed would I be without a neck reinforcement? From what I understand, the normal scale length is 21 inches, so I've shortened it quite a bit.

The neck it 1/2" thick near the volute without a fretboard if that does anything.

Thanks!