How difficult is it backing a 8ft trailer behind Mercedes B+

The biggest issue with backing a small trailer is being able to see what it's doing in time to make corrections. An 8' trailer is so short that it will jackknife very quickly, and because they are typically very narrow as well it WILL be a pain to back with a MH unless you can address the visibility issue. That can be done in several ways; a backup camera is the best, but a cheap and effective way is to attach small flags (when backing) to the rear of the trailer that extend out wide enough to see them in both side mirrors.

I used to tow a small 4'x8' trailer behind my 27' Class C. Without the flags on it, it was impossible to back up more than 10' since by the time it came into view of my mirrors, it was jackknifing and too late to correct. With the flags, it was very easy to back up.

My wife is a rural mail carrier and had to use her jeep wrangler...it was not big enough many days so I made her a 4'x4' trailer for added space. Now THAT lil thing was NOT fun to back up!!

I have a 5X8 trailer. If the backing ever got too (mixed) up, I'd take the motorcycle off the trailer , disconnect it from RV, and back it in by hand. It is very easy to move. Removing motorcycle at destination is generally my goal anyway.

FWIW it isn't too hard to move on level smooth ground even with load on the trailer.

Enroute you should be able to avoid complex backups with the trailer. A few feet of straight backup can be accomplished using back up camera. More complex backups such as 90 degree campsites I'd say just plan of popping trailer off and rolling it in by hand.

OP, another option is a swivel wheel platform that attaches to the back and it follows the tow vehicle. The problem is that most of the weight of it and what you put on it will be added to the rear axle/tires which may overload them.
How hard to back up is a math equation. If the tow vehicle's wheel base (WB1) is about the same as the distance from the rear axle of the tow to the trailer's axle (WB2) it's doable with practice. The greater the WB2's distance (longer trailer) the easier it gets to back it up. The more the wheelbase of the tow vehicle WB1 is from (1 to 1) the harder it gets to back it up. Most MH's have a longer overhang off the rear axle than say a PU which helps in making it easier.

It depends completely on the driver's level of skill.
If the driver has very little experience backing trailers, it can be an exercise in futility, and VERY frustrating.
If the driver has had a lot of practice backing trailers of all sizes (I have known professional truck drivers that could stick a 53 foot trailer into a 10 or 12 foot wide trench in one try, but could not back a single axle trailer with a 16 foot boat on it!), he can do it with little trouble.
I once had a 29 foot Class C, and a tandem axle trailer with a 16 foot boat on it. I could launch the boat with no trouble. However, a previous boat I had was on a single axle trailer, and it was absolutely horrible to try to back down the ramp!
There are just too many variables to make an accurate prediction.
Good luck.

An 8 foot trailer will be very hard to back. I doubt if you will be able to see it behind the B plus short trailers are hard to back.

Measure the wheel base of the B+. Measure the distance from the center of the rear axle to the ball and add the distance from the ball to the axle of the trailer. If these two distances are close to the same you will not have any problems backing it up with some practice. If the wheel base is greater by 25-30% it's going to be difficult and a hitch of the front may be needed.

I have an MB based RV and had a front hitch fabricated/installed for this situation.

BB_TX wrote:
Don't know about behind the B+, but I can tell your the shorter the trailer the harder it is to back due to how fast it reacts. That is especially true when you cannot see it well. My 8' utility trailer is much harder to back than my 16' utility trailer.

Very true. A properly constructed trailer will have the correct dimensions. The distance from the ball hitch to the axle should be twice the distance between the wheels. One constructed that way will be the easiest to back up.

You can't back a trailer very well if you can't see it. A backup camera is a good idea, or if it's a light trailer, put a jack with a wheel on the tongue and unhook and push it where you want it.