Thanks. I've decided on 45k starting stacks (12/12/7/10/6). Looks like we'll be 16 now in the end after a last-minute COVID-related drop-out yesterday.45k starting stacks (12/12/5/11/6 or 12/12/7/10/6) are definitively preferable to 50k stacks that contain T25k chips.
You will have plenty of T1000s in play already with those starting stacks, so color-up the T25, T100, and T500 chips using T5000s, and color-up the T1000 chips with T25000s. Add T5k and T25k chips with 5-chip re-buys (4xT5000 +1xT25000).
For 17 players, that will put roughly 125 total chips in play at tournament finish (plus any re-buy chips), which is a perfectly acceptable amount.
Luckily, there will be some experienced tournament hosts in attendance who can help this rookie with colouring-up. I've watched some videos though and I think I've got now.
Thanks again to everyone for the help - Saturday can't come soon enough now!