Reddit mentions of Diamondback Insight 2 Flat Bar Road Bike - 2016 Performance Exclusive

Do you have a bike at the minute?

I'm sure you're aware that buying a bike from Amazon maybe isn't ideal for a few reasons, but if you're confident enough to assemble it and keep it maintained yourself then there are a few "not terrible" options. This is probably one of the better deals:

http://www.amazon.com/Diamondback-Insight-Flat-Road-Bike/dp/B017TEZORS/

Diamondback are a reasonably big name manufacturer, and they do make some good bikes. Disc brakes could come in useful, and the cr-mo fork should be good for comfort.

Or there's this, which is similar but with hi ten forks (generally a bit less comfortable) and V brakes:

http://www.amazon.com/Diamondback-Bicycles-Complete-Performance-Metallic/dp/B0132I8YQS/

Bit of a wildcard, I don't tend to like suggesting single speeds but a full cr-mo frame should be solid and comfortable, and the drop bars can help with comfort on longer rides:

http://www.amazon.com/Nashbar-Single-Speed-Cyclocross-Bike-49/dp/B00F52JWPC/

Whatever you get, I'd probably consider putting some wider tyres on it to start out with. Might need to see it first to check the tyre clearances, but most hybrids are pretty generous and can generally take somewhere around max 38-45c tyres. A wider tyre will have more air in it to support a heavier rider, helping to protect the rest of the bike, make it more comfortable and give it better performance off road.

Honestly, I wasn't expecting to find any bike that I would be willing to recommend. But I did find one. And one only. If you don't want to buy this bike, do not buy any other $400 bike from Amazon in order to do this trip. If you do buy this bike, do not buy any size other than the xl.

As this bike is going to come somewhat disassembled, keep in mind that you, or someone is going to have to finish assembling the bike.

http://www.amazon.com/Diamondback-Insight-Flat-Road-Bike/dp/B017TEZORS/ref=sr_1_1?s=outdoor-recreation&ie=UTF8&qid=1462684459&sr=1-1&keywords=bicycle&refinements=p_36%3A-40000

I am recommending this with all due caution. Between it being a low end bike, and coming partially assembled, and the fact that it is a flat bar bike, which are not generally considered ideal for distance riding, it is difficult to enthusiastically recommend getting this bike. Some people have difficulty riding 10 miles on them without hand fatigue. There was a guy who posted recently who rode across the country on a flat bar bike. But you don't know if you will be able to do 60 mile days on a flat bar bike.

My suggestion would be to rent, or to buy a more expensive bike, and sell it afterwards, getting most or all your money back rather than buy a bike without getting a chance to even test ride it.