As someone who missed the kickstarter, and has been anxious to purchase this game for a couple of years now...
I'd have to say, if you started taking pre-orders and offering refunds at the present time, my suspicion is that it would have the exact opposite effect that you are aiming for. In other words, I think there will be more negative (than positive) fallout, and it would create more problems and contribute to your angst about the topic, rather than alleviate it.
I think getting your KS update up, and feeling out the overall vibe of your backers after they have some time to digest it, is your first and most important step.
After that... If a few folks wanted refunds, then maybe you can take it on a "case by case". Ask them to contact you through xyz, and have a conversation.
If by some chance, a lot of people are screaming "refund" after you post your update... then, I guess you better get to work getting LT to a playable state
I think you'll be fine, man. Just keep your eye on the target, and let folks know that you are working... Heck, even a selfie with your monitor photobombing you in the background every now and then would probably go a long way for a lot of folks. They get to see "Hey, Josh is kicking ass, hard at work", without you having to devote man hours to "keeping folks updated" with long ass devlogs, etc.
As long as folks see you are present and doing work (even if not posting lengthy diary entries) you will be FINE.