You have a pretty wide array of cameras from which to choose. So to narrow things down a bit the first thing I'd do is eliminate all cameras that require a top-hat or other accessory to focus closer than infinity with your 300mm lens. That eliminates anything with a 12 inch or shorter bellows such as Wista.
For me it would also eliminate the Shen Hao that in its normal configuration has a 12 inch extension. However, another couple inches can be added by fiddling around with base and axis tilt, which moves the lens out in front of the camera bed, which has always seemed to me like a bad idea from a stability standpoint though some Shen Hao owners may disagree. Or maybe there are other versions that have a longer normal extension, I'm not familiar with all the different Shen Hao models, just the basic one that I owned briefly (briefly because it wasn't accurately described by the seller, not because I disliked the camera).
Tachihara is cutting it close with its 13 inch bellows. The extra inch will allow you to focus closer than infinity but not as close as you could with cameras that have a longer bellows. I used a 300mm lens with a Tachihara and the loss of some close focusing distance didn't bother me, maybe it wouldn't bother you either.
A Chamonix might fit your needs the best. It sells for well under $1,500, weighs around 4.5 pounds, is very well made, has plenty of movements, and has a 15 inch bellows which is fine for your 300mm lens.