Only if you ride those 80 km really slowly. Peter White indicated a leak rate of 20 psi/full day or a little less than 1 psi/hour and that's consistent with what I saw when running tubulars. So start with a little extra pressure (5psi) over your normal amount and at the end of 10 hours you might be down to 5psi below normal. Hardly enough to worry about.

But I agree that the aggravation of needing to pump up every morning on a tour would weigh against the use of latex. However, there is also a rolling resistance advantage, albeit not as great, for going with the thinner butyl tubes vs. regular weight ones and those have a much lower leak rate (but still greater than the thicker tubes). Not a big effect, but likely larger than the effect due to the weight difference alone.