In reply to buzby:
> Anybody been and care to share their experience.
I have. Kinda sorta.
I joined an organised sea kayak expedition on the MV Cuma last summer. ( https://www.zoenewsamguiding.com/st-kilda-expedition.html )
The weather was not kind however. We almost didn't get there at all, every morning the shipping forecast basically said "Not today - maybe tomorrow." Just as we'd given up on ever getting there, Murdo (the Cuma's skipper) told us he'd seen an opportunity for a quick day trip and we were off.
Murdo dropped us off at the North West tip of Hirta, close to Stac Shoaigh, and we paddled along the coast and around the tip of Dun to meet him again in Village Bay. The wild weather had all been coming from the North East for the previous days, leaving that coastline unusually sheltered and we enjoyed a gobsmacking journey in brilliant sunshine on a mill-pond sea getting right in and out of the many caves at the foot of the amazing sea cliffs along that coast. Conditions were anything but mill-pond on the Eastern side of Dun, the last mile or so of the day's paddle was a wee bit hairy.
The plan was to get the kayaks back aboard the Cuma, have a bite to eat then take a quick walk around the island. In the end there wasn't enough time - the weather was closing in, wind swinging round more Southerly, and along with all the other boats in Village Bay apparently, we had to leg it. The return journey was hellish, I have never been so seasick in my life.
So apart from a quick swim from my kayak to scramble up a ramp to a ledge on one of the sea cliffs and take a group photo, I didn't actually get to set foot on dry land there.
There were quite a few boats anchored in Village Bay while we were there, including a pretty sizeable cruise ship. There seemed to be a bit of hustle and bustle going on at the time with some construction work on the quayside for the military base. For the cost of it, I wonder if an overnight stay on the NT campsite there might not disappoint a bit in the sense that it might not feel quite as remote as it actually is.
Guessing a bit having not walked on the island, I also wonder if the more impressive sights you'd get to see on a day trip might not actually be from the sea. Looking at the link Vanessa posted, I see their trip includes a quick visit to Boreray and the stacks. There's no mention of the boat from/to Skye going that way. (It isn't en-route from Harris or Skye.) I'd be keen to see that.
I've never been, but have you considered the possibility of a trip to Pabbay and/or Mingulay instead?