That is a common finding and it's all about how you interpret the papers. If you cram the entire temperature gradient into a 10 gallon enclosure, then yes, I would limit it to about 28C. However if you have a more appropriate, larger cage, then by all means, offer the larger range.

A more critical evaluation of your sources can also help tell you where the information comes from. Look at the references/citations. Is the information primarily from personal opinion, care books, studies on natural history, etc. The veterinary literature is great in some aspects, but in my experience, not the greatest on husbandry (are you referring to the BSAVA vet textbooks?). You have to understand that veterinarians see all the bad... people take their animals to them when they are ill and dying. Thus you might think that they are less inclined to recommend the higher temperatures because they probably have seen a whole lot of animals suffering from the improper use of these higher temperatures (see 10 gallon example).

Also note this when acknowledging what your target audience will be. I would not assume that it is going to be the advanced hobbyist, but the crowd first getting in to snake keeping. Thus simple concepts have not yet been mastered, so the inappropriate use of information will be rampant. So with that considered, perhaps using a moderate temperature range would be safer.

Ian