As has been mentioned before, permethrin does not repel bedbugs nor kill them on contact. They need prolonged exposure (like a couple of hours or more) to a permethrin treated surface before they die.
I don't know what evidence you have that such a long exposure is required to kill bed bugs. Earlier I referred to a study that indicated that a one minute exposure to ActiveGuard, a permethrin treated fabric used for mattress encasements, was sufficient to significantly reduce the likelihood of the bedbug attempting to feed by about half, and a 10 minute exposure further reduced this about another 10 times. That is, to around 2% of the rate were the fabric untreated. This particular study did not discuss whether there were differences between highly resistant and less resistant species.
A mortality study using the same fabric observed a mortality rate of 87% to 100% for non-resistant beg bug species within a day after just 30 minutes exposure. The mortality rate for the resistant species was only 4%.
I think these results provide a significant challenge to the view that, even with a permethrin treated liner or sleeping bag, bed bugs will still get a blood meal. If any do, it appears it will be a really quite small proportion of those that might using an untreated bag or liner. The effects of even a short period of contact are to reduce both the likelihood of attempting to feed, and then the likelihood of successfully feeding.
Edit: Here are the sources I have used:
Susan C. Jones, Joshua L. Bryant, Frances S. Sivakoff, Sublethal Effects of
ActiveGuard Exposure on Feeding Behavior and Fecundity of the Bed Bug (Hemiptera: Cimicidae),
Journal of Medical Entomology, Volume 52, Issue 3, May 2015, Pages 413–418,
https://doi.org/10.1093/jme/tjv008
Jones SC, Bryant JL, Harrison SA. Behavioral Responses of the Bed Bug to Permethrin-Impregnated ActiveGuard™ Fabric. Insects. 2013 Jun 7;4(2):230-40. doi: 10.3390/insects4020230. PMID: 26464388; PMCID: PMC4553521.