I'd advise looking into hot weather climate boots, with plenty of vent patches to let your feet breath.
if you are going to be putting a lot of miles in, DO NOT go cheap on boots, my suggestion would be to get some Altbergs custom fitted to your feet.
have a look at these.
http://www.altberg.co.uk/Web/military.jsp
Jungle microlite
Desert microlite
Mountain Desert
theres even the good old fashioned sneeker, very lightweight and thin, but i think even these would end up being to hot and stuffy
also check out LOWA, they are a bit heavier and clunkier for want of a better word, but they are extremly comfortable for walking over long periods of time.
http://www.aarondistribution.co.uk/
elite desert
elite jungle desert
and if you prefer the lower cut boots look at the zephyer mid tf fesert.
my experience with meindl boots have been very poor, just dont hold together, their desert boots fell apart for me after a month, the sole started to seperate and the stitching was disintegrating, on top of that i found them uncomfortable for my wide feet.
What ever you do i'd would highly advise against goretex/waterproof linings, once they get wet inside it will be an absolute nightmare to dry out and you will find your feet sweating like hell, much better to have a nice thin lightweight boot with plenty drainage that will dry quickly.
the key thing here is to find a boot that keeps your feet as cool and dry as possible, you start walking with wet feet either through water or heavy sweating you will go man down fast.