Common breaks and free axes for overlapping lattice histograms

What is the required incantation to achieve an overlapping, faceted lattice::histogram with common break points (across groups, but potentially varying across panels)?

For example, assume I want the total range of the data (groups combined) for each panel to be split into 30 bins.

Example data:

library(lattice)
set.seed(1)
d <- data.frame(v1=rep(c('A', 'B'), each=1000), 
                v2=rep(c(0.5, 1), each=2000),
                mean=rep(c(0, 10, 2, 12), each=1000))
d$x <- rnorm(nrow(d), d$mean, d$v2)

Using nint=30?

p1 <- histogram(~x|v1, d, groups=v2, nint=30,
                scales=list(relation='free'), type='percent',
                panel = function(...) {
                  panel.superpose(..., panel.groups=panel.histogram, 
                                  col=c('red', 'blue'), alpha=0.3)
                })
p1

Above, the bins are consistent across groups, but (1) the x-axis limits are shared across panels (problematic when the x-axis range varies substantially across panels - I really want the 30 bins to be calculated individually for each panel), and (2) the y-axis is cramped when using type='percent' (it should extend further).

Using breaks=30?

p2 <- histogram(~x|v1, d, groups=v2, breaks=30,
                scales=list(relation='free'), type='percent',
                panel = function(...) {
                  panel.superpose(..., panel.groups=panel.histogram, 
                                  col=c('red', 'blue'), alpha=0.3)
                })
p2

Now the axis limits look good, but the bins width varies across groups.

So...

How can I achieve an overlapping, faceted histogram that has shared breaks across groups, but has axis limits that fit the data for each panel?

(I realise that ggplot is an option, but I want the figure style to be consistent with my other lattice plots.)