Do you need a braking system on the towed: YES. no question about it
Should it be a brake buddy: NO, I don't think so
Either here, or on RV
is a post titled "Home made brake buddy"
You should read it... (NOTE: the title is a joke)
Here is a bit of fact.. When you do all the math to calculat how far a vehilcle will skid with all wheels brakign. It does not much matter if you are driving a 2,000 pound mini-car or a 160,000 pound steel hauler.. Weight, which is mass times gravity, factors out and the ONLY variable that counts is SPEED (whch by the way is squared) so a Semi truck going 20 mph will skid exactly 4 times as far as a mini-car goign 10.. And I might add the reverse is also true, the car goign 40 will skid exactly 4 times as far as the semi going 20.. Why, because speed is squared and it's on top.
However if you have only PART of your wheels brakign
now you have the weight of the braking vehicle (Towing vehicle, motor home) and the MASS of the consist (motor home plus trailer (towed car) so the math matical formula gets a lot longer,, and so does the skid
Oh, the basic formula for skids.
5 1/2 feet times (Speed/10)^2
That yeilds 22 feet at 20 mph, 88 feet at 40 mph at 60 mph it's 198 feet
Of course that assumes a "Average" coefficient of friction between tire and road which is something you almost never have..
This also suggests tire condition matters... It does not on dry pavement, it does on wet or snow or ice however.