Berachos 13b Sugya d'Prakdan Lo Yikra Kriyas Shema - Part I

The following post of a slightly sensitive nature, and as such, I'll be using more Hebrew/Aramaic than I usually do. To understand it fully, I recommend seeing all the sources in the original. Perhaps someone will be kind enough to teach me how to post in Hebrew, and I'll be able to post the sources myself... (I can already cut-and-paste from mechon-mamre.org!) I'll try to post links to web-based sources where I know of them. Also, I'll probably post this over a few days.
B'zeh hachili, b'ezras tzuri v'goali:
The gemara in Berachos 13b: אמר רב יוסף פרקדן לא יקרא קריאת שמע מקרא הוא דלא ליקרי הא מיגנא שפיר דמי והא רבי יהושע בן לוי לייט אמאן דגני אפרקיד אמרי מיגנא כי מצלי שפיר דמי מקרא אע"ג דמצלי נמי אסור והא ר' יוחנן מצלי וקרי שאני ר' יוחנן דבעל בשר הוה - R' Yosef says: A prakdan should not recite the Shema. (Rashi explains: Prakdan - one who lies on his back, face-up.)  The gemara asks, we can extrapolate from R' Yosef's statement, that although a prakdan may not recite the Shema, one may sleep in that position. The gemara says that this would be inconsistent with R' Yehoshua ben Levi's cursing those who slept in the prakdan position (Rashi - shemah yiskasheh eivoroi while he's sleeping v'nirah l'rabim, which is a derech g'nai), which obviously indicates that one may not sleep in the prakdan position. The gemara answers, one may sleep in a prakdan position if he's slightly tilted to one side. However, one may not recite the Shema unless one is lying completely on his side (Rashi - because otherwise he is accepting the yoke of heaven upon himself, in a haughty manner). The gemara asks, why did R' Yochanan recite the Shema even though he was only tilted a little bit to the side? The gemara answers, that there were extenuating circumstances in R' Yochanan's situation, in that he was extremely heavy.
The bottom line after the gemara and the Rashi is: A man may not sleep on his back unless he's tilted a bit to one side; a man may not recite the Shema lying on his back - he must lie completely on his side. 
Now the cliffhanger: According to Rashi, the whole problem with sleeping in the prakdan position is the derech g'nai of being nirah l'rabim. If so, would it be permissible to sleep in the prakdan position in a locked, or dark room?
To be continued...