Best two wheel tractor options out there that I have found are the old Planet Junior 300 and 300A seeders, but they are not great at metering precision, or depth in unprepared ground. I have a Planet Jr. rig that was originally for their two wheeled tractor, that I have 4 seeder units for.
Lots of Russian/Eastern Euro vac seeders out there, that are retailing for pretty reasonable prices compared to the arse raping prices of similar tech in North America. Am comparing the base price on one of the Euro sites at around $2K, vs prices in the $15K range for used similar machines. Ouch!
EG:
Сеялка вакуумная - YouTube , which shows some pretty basic technology. I have been mulling over the use of steppers instead of the variable speed DC motors in the video, and using something like a PLC or embedded computer like a Rasberry Pi, as one example, to operate the speed of the rotating drums, to allow programming in the spacing based on wheel speed sensors, so that various spacings can be precisely set, rather than by trial and error.
The vacuum source being used in these is essentially a leaf blower fan, either driven by a gas motor, or off the PTO of the power unit, something that would also be pretty easy to work out with the PTO of the BCS, I think. The PTO versions that run on a 540 PTO use a couple step up pulleys to get the fan up to working speed.
Check out the seeders available on Alibaba.com too, if you are looking for inexpensive but workable tools. Many of the sellers there will ship in single unit qty, delivery times may be months, and the support from the manufacturer might revolve around your befriending a recent immigrant to translate (which is to say, pretty much on your own) but if you are half handy, like as not you can make one work.
Traction is going to be an issue. OK, might be an issue. Might consider steel paddles for the wheels.
I think the Hoss would be sorta OK as a garden tool for a home garden, if even that, but I would want to look at stuff more like the Jang or similar moder seeders that already have some use in tractor drawn applications to get the kind of reliability I would want for a couple acres at a time of use.
Mind, you can buy a decent small grain drill and a beater grade small tractor to pull it, for the price of most of the commercially available options, including the Jang, at ~$1500-$1800 per unit (each individual row)plus spares (needed for each different size seed, times the number of rows)
Root through the back posts here. There was a home build project by a guy in Australia IIRC, sometime last year, posted up, that looked pretty do-able if you were half handy. All the commercial small scale units are insanely expensive, compared to their actual full scale counterparts.
Oh yeah. Barley. Barley for malting, got me looking at seeders and seeding in small plots.
Cheers
Trev