If you want a backpack and trolley system I think that's silly! Sorry
A back pack will act as both! Saving you £££'s All you do is buy a sack trolley and bungee your backpack to it.
The back pack is amazing. You will love it.
All you will need is:
1x backpack = £200 + Vat
1x 2x4ft pole = £37.50 +Vat
1x 18ft pole = £80.00 + Vat
1x trolley = £20.00 inc Vat (metal sack trolley with pneumatic tyres)
2x bungee's = £2.00 inc vat
Total = (roughly) £395
Then you have to purchase equipment for purifying your water.
If you go down the di route (soft water area) it might cost £100 to get a di vessel full with resin. That would get you going.
If you choose a ro system that could cost you anywhere between £79.99-£400 or £500.
The choice is yours.
That is just a rough guide. Dont quote me on that prices.
Hope that helps you out