Alternatives to suit and tux?

My fiance and all groomsmen will be wearing kilts with vests only, no jackets. Jackets felt too formal and he looks like a football player in one lol maybe he could just do khaki pants with a vest and dress shirt?

Slacks and button down with suspenders or vest with a bowtie or tie! Even more casual would be jeans and a button down with or without a tie

Here are a few pics I found!

I love the look of a bow tie and suspenders. It could go well with your vision.

Mine wore suspenders

We’re getting married on the beach, so we wanted to avoid suits/tux’s as well. He’s going to wear linen pants and shirt. The shirt has a simple embroidered pattern down each side of the chest which mimics the look is suspenders. My son has a matching outfit but with shorts instead of pants.

Currently we're thinking of only doing vest and tie (no jacket) for groom, and possibly suspenders and ties (or bowties?) for groomsmen. It will be hot and an outdoor ceremony so we want people to be comfortable.

A button down with a vest, and either khakis or jeans (depending on how casual)

Our guys wore gray slacks with matching vests over a shirt and tie.
I think vest or suspenders sound awesome for a rockabilly vibe