I got 2 Duracell 6v Golf Cart batteries at our local Sam's club for around $90.00 a piece and have been very please with the performance from them. They have about the same spec's as what you listed for the Excide. I had the Excide 12v deep cycle battery in another trailer and always had problems with it taking a full charge. I had the store replace it and had the same trouble with the next one.
My experience is that most things are cheaper away from rv stores/dealers. Also, I think any familiar name golf cart battery will work fine because they have to take a lot of abuse in a golf cart and so are built to take it.
2015 Crossroads Cruiser Aire CAF27RL, 2018 F250 diesel crewcab SRW 4WD short bed, Trailer Saver hitch with Reese adapter on Ford OEM underbed 5th wheel connector.