Water storage dilemma

[threedogs]

In my camper I have a dolium 55ltr water tank that gravity feeds via a 1/2" tap on the out side.
flow rate is adequate but could be better.
This tank will fit across the floor in the back if I go fishing solo and leave the camper at home.
What I want to do is fit a water tank [black caravan style] under the camper to help balance
the weight a bit better. Being under the camper I will now require a pump of some description to draw water up to the tap,
Fill point will be where the fuel filler was via a plastic deck fill from a boat. what i need to know is what size pump is right ?
I've seen cheap ones that will do 5 LPM is that slow or ok.? I have plenty of 12v power available. simpler the better
http://www.ebay.com.au/itm/251677365256?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.com.au/itm/190561357971?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[blocko05]

58393
Hi mate,

I run one of these in my camper and it works well. I have a 59 liter water tank that sits behind my axles. I have needed to run a re stricter on it to slow the water flow down to 2.5 liters per minute for the sink.