I'm 5'1" and I dive single HP80s (great little tanks - I have 3) as often as possible.
When I started in doubles I first used LP72s and felt they were overwhelming. (First day ever in doubles Jan 2010)
I later started cave training and was told by one of my instructors that few would dive with me unless I was carrying enough gas such as LP85 pumped to cave fills - even though I have a low SAC rate.
And in just a few dives of practice, these are now my preferred tanks in a drysuit. They do trim out nicely, and I've learned how to move in them (carry the weigh on my hips). The important thing with doubles is the weight of the regs and manifold had me face planting. Moving to the longer tanks, further down my back, wing further up the plate, I was finally able to balance out and have OK trim most of the time. (Oct 2012)
For warm water here in the Keys, I dive AL80s in rash guard or shorty or wetsuit. (me on the left)
If I can do it at 51, you can too. It's really about distributing the weight so it works for your horizontal trim, and then practice to getting used to it. And no I'm not particularly strong.
Yes, after a long dive, many times I sit and rest before moving tanks (or get help from my sherpa
)
It's been a long slow process for me (not something I ever felt compelled to rush). Once you are able to remain in horizontal trim you don't notice the difference. I've learned from watching nad reading other short women like TS&M.
Here is another discussion on tiny doubles
http://www.scubaboard.com/forums/tanks-valves-bands/449338-tiny-doubles.html
Good luck with your choices and growing into your technical diving.
---------- Post added January 8th, 2014 at 10:35 PM ----------
One more comment...if you are concerned with the weight of tanks on your back, why not just go straight into sidemount. That way you only carry one tank at a time to the water and gear up in the water. On a boat, you just unclip the tanks and pass them up one at a time.