Decades ago,an English company offered an inflatable bulbous nose for caravan trailers,which would convert a 'shoebox' into an 'Airstream.'(at least at front)
If memory serves me,it was good for a 28% drag reduction.I had a graphic,but lost it in the PhotoBucket takeover.
A study of contemporary inflatable advertising (recently Halloween pumpkins) will illustrate the concept.And any 12-VDC automotive HVAC blower fan would be adequate for inflation.Gentlemen,Start Your Sewing Machines!