We bought a new TT last year. We had RV's 20 years ago and decided it was time to go back to one.
We got the basic things..sewer hookups, water hoses, mirrors for truck, hubby cut up some planks for levelling, lots of hydro extension cords. He also takes a drill along for the levelling jacks. Hubby also has a complete set of tools, you always have something to fix. Extra pins for sway bars etc. Extra bulbs for outside lights and fuses.
We have bought something new every time we go out, LOL
As far as what you need inside for everyday living I could give you my list of what I filled our 27' with. Hubby said he can't think of one thing I do not have to be able to ..cook a gourmet meal, fix things broken, deal with minor medical issues etc. There are 2 of us but we are set for 6. One thing...don't fill with little appliances, only one we have is a toaster.
As suggested be close to a walmart or a hardware shop
