Image overflow in FOP

Hi !
I'm using FOP 0.95 to generate a PDF from an XML document.
I'm using XSL-FO to make the transformation and i'm having
difficulties with images, especially making them to fit within page or
to jump over the next one.
All these images are SVG (within instream-foreign-object). The SVG is
made of a large JPG background imported with <svg:image> and one or
several <svg:path> or other basic shapes.
The only constraint i want for the images is to fit the page width,
and conserve aspect ratio.
That i managed to achieve it. But the problem is that the image
overflow the page height whenever there isn't enough room left at the
end of the page. Here is a screenshot of what the problem is:
http://img444.imageshack.us/my.php?image=imageoverflowbj6.png

What i want to do is making FOP to do a page-break when the image
can't fit into the page.
I tried every combinations of keep constraints with no luck.
I even tried to fix (or remove) the width and the height on the
instream-foreign-object but FOP still doesn't want to jump to the next
page :'(
Here are some screenshots of the result:
 - without width
http://img241.imageshack.us/my.php?image=imageoverflowwidthaz5.png
 - with smaller height (but still big enough to make the image bigger
than the space left at the end of page)
http://img504.imageshack.us/my.php?image=imageoverflowheightjs7.png

We can see that the image is very well scaled up/down but i can't make
FOP to break-page :'(

Here is the incriminated piece of code (corresponding to the first screenshot)
<fo:block>
 <fo:instream-foreign-object width="100%" content-width="scale-to-fit"
content-height="scale-to-fit">
  <svg:svg viewBox="519025 -6702573 5363 4051" height="2430px" width="3219px">
   <svg:image height="4051" width="5363" y="-6702573" x="519025"
xlink:href="file:///C:\bdd\docs\cartes\Scan25_Georef.jpg" />
    [some paths, rects and texts]
  </svg:svg>
 </fo:instream-foreign-object>
</fo:block>

It seems like one of the FOP known issue in the LayoutEngine, but i'm
not quite sure because i use instream-foreign-object instead of
external-graphic:
http://xmlgraphics.apache.org/fop/knownissues.html#Layout+Engine
(external-graphic don't shrink)

My questions are:
 - is it possible to do what i want (having a page-break whenever it's
needed) with instream-foreign-object (and with FOP) ?
 - in case it's not, how could i calculate the space left at the end
of page to decide whether i put a break-before="page" on the
corresponding block or not ? I saw some xpath in FOP testcases which
tried to access some kind of "internal properties" like viewports
etc... and i wondered whether it's possible for me to use these path
to retrieve the remaining free space (and for my culture: are these
paths part of the standard or specific to FOP ?)

Thanks in advance for your help, i'm stuck with this issue for days...

Some ressources i found (and tried whenever it applied to my pb, but
with no luck):
http://www.nabble.com/Image-overflow-td5982795.html
http://www.nabble.com/0.94-AND-0.95b-Images-to17627201.html#a17629647

For those who can understand french, here is a more detailed
description of my problem:
http://forum.hardware.fr/hfr/Programmation/XML-XSL/debordement-image-generer-sujet_118855_1.htm