There are many developments that have such Covenants. They were normally introduced to protect all the residents of the develoment from intrusions, commercial or unsightly that could harm the area for all, and possibly adversely affect market values. For instance things such as farm animals are usually banned to stop anyone trying the 'Good Life' scenario. Caravans are included not becasue of you particularly, but because someone may decide that using it as living accomodation is a good idea, or have more than one. Where do you draw the line?
In additon your innocent caravan could lead to a commercial vehicle (ice cream van perhaps) which could lead to trade being carried out at all hours.
As mentioned the chances of a prosecution are rare mainly because the other residents would have to meet the initial costs, however, not impossible, especially if a Management Company is involved, in which case you meet all the costs if the case goes against you. Also your neighbours are faced with the dilemma of not necessarily approving of what you are doing, but not wishing to cause upset. Nobody wants to be seen as a 'spoilsport'. However, not receiving a complaint does not mean that people are in agreement with what you are doing.
You must decide yourself if this is what you want. You must have been aware of the Covenant when you bought the property, or your solictors were amiss in their duties to you in the Searches carried out before purchase. You could possibly have grounds for a claim against them.
It is back to the old question of whether your actions are good neighbourly, or not. Only you can answer that.