Here is my wife (she painted herself out of my picture as she hates cameras) baling with our little a Kubota L285 (26.45 PTO hp maximum at WOT only around 23 hp with throttle at 540 rpm where you run the baler and no live PTO either). We only bale between 4.5 - 7 acres relatively flat acres each cutting and do drop on the ground. I think I could pull a small wagon if I had one but I do not. Really, I have no interest in getting a wagon. I prefer to use my flatbed trailer behind a pick-up truck to collect the bales. It keeps me out of the baler dust, allows me to easily operate as a one-man operation if the wife goes on strike, and I can use the trailer for other things too.
My baler is a New Holland 65 compact baler which is the smallest of the vintage balers that can be purchased cheaply, but there is actually brand new mini-balers (e.g. MicroStar) out there designed to operate on really tiny tractors but they are expensive.
Here is a list of balers that I would consider to operate with a compact tractor:
a) Micro-Star or other mini baler manufacturer (New and expensive like $15k)
b) NH 65 compact baler (old,hard to find one but relatively cheap if you do, and easy parts availabilty).
c) Ford 520 small like the NH65 but the Ford will be nearly impossible to get parts for.
d) Any NH model the number 66 - 273, but skip the 76 and 77 series balers which are huge monsters. (A bit bigger than the NH 65 or Ford 520, but still low capacity low hp balers and easy parts availibility).
e) John Deere 14T or 24T. (I would prefer the 24T over the 14T. A bit bigger than the NH 65 or Ford 520, but still low capacity low hp balers and easy parts availibility for the 24T. 14T you may have to retrofit some 24T parts).
For the most part the New Holland and John Deere balers will be in excess of 40 years old so plan on doing some repairs to keep them operating. Unfortunately, modern small square balers from the mainstream manufacturers are much higher in capacity than the vintage units and therefore take much more hp to run them.
Literally, Hours worth of reading on this subject if you do some searching.