It sounds like this may be a reactive airway exacerbation with "silent chest".
If so, and he perked up with the BVM, with accompanying increase in sats, I would choose to go the pharmacological route starting with side stream combivent (5 mg salbutamol/500mcg ipratropium x2), then Mag Sulfate drip @ 2g in 50mL NS and 125 mg Solumedrol SIVP.
I would keep my intubation equipment ready but I only have access to RSS with fentanyl/versed so this would be employed as a secondary resort to pharmacological interventions.
In regards to your question with Epi IM for Status Asthmaticus, in our protocol it is in relation to intubation. If we get to the point for intubating a near death asthma then we can give Epi IM @ 0.3 mg or 0.1 mg IV 1:10,000
I cannot say though that I have used this with experience and only have had moderate to severe asthma pt's on my practicums so far that we used drugs for and did not even consider intubating any of them. That is partially due to very short transport times as well though. Also having co response on serious calls we had the manpower to do our interventions on scene in a relatively short time span.