I am not keen to try the patience of Dale or the kindness of the List-- but just to very briefly clarify to anyone I might have confused: my blowouts occurred were while the bike was on a stand and usually just after or a few hours after I had attempted to get the tires to inflate to a more normal range of pressure, ie above 50psi and not while (and hence because) I was riding them with abnormally low pressure. My plan was to try to get them up in 5psi increments at least to 70-75psi (since I had no wish to ride them at really low pressure) but I never got them much above 55psi without either a blowout or rapid budge in the sidewall down at the top of the rim. And yes, I was careful about choosing rim tape-- fearful of precisely the problem of spoke puncture described. Thanks again to you all.
Guy Lesser
Brooklyn, NY