Waistcoat only?

[Tenmiles]

I live in southern California, where it has already hit 32 degrees (90 in Farenheit) and is likely to remain in that range for the next six months (we have two seasons here; a few months of "Winter", which is basically what you'd expect Spring to be like, and "Bloody Hot", which is all the rest of the year).

Though I look forward to a nice tweed jacket for sharp-looking daywear, seasons permitting, in actuality it'll be unfeasible to wear one much of the time 'round here.

However, in the interest of still looking sharp and stylish, I'd like to compliment my kilt & shirt with a nice tweed waistcoat for more regular day wear.

With the disclaimer that I've already been told how "official" I should consider the "THCD Rulebook" to be, I just wanted to ask: Is waistcoat + kilt (sans coat) a conventional thing? Or is it something looked down on by purists?

(Further disclaimer: the answer to this question will not influence my decision to wear what I want; I'm more curious so that I can be fore-armed when dressing for going out to casual situations where I might encounter others who'd be in a position to have an informed opinion on my attire)