I can see a number of potential issues arising from ambos carrying antivenom. Firstly the question of identification. ID of the snake even if it was caught or killed would in the majority of cases have to be considered unreliable unless there is a genuine expert present and I don't mean enthusiastic all knowledgeable amateurs or bystanders. Even if a snake was correctly identified say as a copperhead...what antivenom should be given for a copperhead bite? So ambos would therefore also have to carry SVDK's to identify the immunotype the venom belongs to. There is then an additional delay for swabbing the bite site, incubation of the test vials for 10 mins at a recommended 22C - 24C, repeated washing of the vials (7-15 times), adding further reagents then observing colour change for upto 10 mins. All time consuming. Then there is the additional risk of AV being administered just on a positive result from the SVDK without any signs of clinical envenomation. ( I have first hand knowledge of this happening in a hospital. )
So to me first aid is the key, trap the venom at or close to the bite site buys the victim a LOT of time to get medical help and transportation to a hospital.