I use a small pole for bottoms. If you use the same connectors, you can change over in seconds. I use a backpack for the ones with difficult access, and a DIY trolley for the rest of the work. Have a look as Matt's DIY WFP site before you decide which trolley to buy. It really is easy to build your own, Having said that, the price you quote for the trolley is very reasonable. Welcome to the world of WFP. I was trad for 12 years before going WFP. A bit of a late convert at the time being 63.
Good luck Dai