Congratulations on getting your Fiesta - had great times in ours when the kids were growing up.
Worth getting it properly serviced by a registered caravan engineer, who will know what they’re looking at with the running gear, brakes etc; at the same time checking out the gas and any other habitation systems. You get peace of mind, and fairly cheap for folding camper. Mobile Caravan Engineers Association
I bought a 5 year old Anssems trailer and the first thing I did was change the wheel bearings. You can tell if they need replacing if there is excessive play when rocking the wheel side to side, you might feel a bit of play but any more than a small click indicates a problem.
If you lift the wheel off the ground it should rotate freely and spin quietly, if it’s loud or grumbly that is a sure sign to replace. Also if the wheel doesn’t spin freely this is a definite problem that needs to be sorted straight away as it will heat up while towing and destroy itself.
your Fiesta has a AL_CO chassis fitted to it. The information from AL-CO says that the bearings are sealed, and will last the life of the vehicle and should not be disturbed. I have seen service engineers removing the wheels and brake drums, to check the brake linings, This is not recommended by AL-CO they have put an inspection hole behind the drum for this purpose.