I will caveat this by saying I am pretty bad at estimating sizes, and it is not my arena, so I may be wrong about how big it is.
I ride in an arena that is more or less that size for much of the year, I think it is probably more than 50ft wide though, our 20m circles feel just a bit smaller than in a regular arena.
How the farm owner deals with some of the space issues is by keeping an equal length, but wider pasture next door to the arena nicely mowed, so if it’s not too wet or dry, that space is available. In the winter we often work in one of her pastures that is much bigger than a standard arena as well. The farm owner also does a lot of work on the dirt road she lives on, but obviously having that option is super dependent on where you live/the horse you are riding.
Her feeling is that it is less than perfect, but it was there when she moved in, and it is free to keep its current size.
I do some jumping in it (and sometimes out of it, the fence between the arena and the pasture next door has a couple permanent jumps in it), and don’t find that we have issues with running into things or that we are super limited as to what we can do. But it does get difficult to have more than about 3-4 jumps in the arena (one or two of the “jumps” can be small grids without any issues though).
In a smaller arena I always have to have a plan, which my trainer shouts I communicate to my horse before we are already where I meant to be turning. :lol: So in that way it is a good thing for me!
It does get a bit boring at times, but it also encourages me to be more thoughtful about planning my rides with a specific goal in mind, and my trainer has come up with some really creative ways to use the small space as well!
It is nice to occasionally have some more room to stretch out in though, either on or off property, but I would bet if you have some non-arena ridable space on your farm, or a nearby place you can get to semi-frequently you’ll probably get by just fine, unless you need a reason to expand the arena, and the money to do that, because larger arenas are pretty much always nicer than smaller if you have a choice!