I also have a mini-ex, specifically a Yanmar Vio55. Steep ramps feel uncomfortable, but they load ok. I have tilted the trailer some to lessen the ramp angle when loading into a dump trailer. The problem I have had in a dump trailer or any short trailer is that I can't put the weight in the correct spot. Too much tongue weight, or too much rear bias. And you simply can't tow safely if you have too much weight rearward, it's a good way to get in a wreck. Come to think about it, I've never had this current excavator in a dump trailer, but have done some 7500 lb machines. That still wasn't ideal in a 14' trailer.
We sell trailers and everyone wants that one perfect trailer that is a dump trailer, an equipment trailer, and a car hauler. I do too, but it doesn't exist, or at least not without a bunch of compromises. You have a little more flexibility if you are pulling with an F450-F550 size as you can load the tongue up much heavier and get away with it.