I carry a basic style tool box, the kind with a lift-out tray. It has all the frequent use tools, a set of screw drivers, hammer, Robo-grip channel locks, wire various pliers and wire strip tool, hammer, vise grips, 1/4 inch socket set, etc. The large 3/8 socket set is in its own box and I have stopped carrying the 1/2 inch set due to lack of use. If I ever need one, I'll borrow it or resort to a shop. I also carry threeroll up tool wraps, two with SAE & metric box/open end wrench sets and another with miscellaneous low-use tools like files, snap ring pliers, rivet tool and such. I have found the tool wraps fit neatly into nooks and crannys in the bays and consume far less space than when I had them in a standard tool box. Last, I have two shoe box size plastic containers with various tapes, glues, sand paper, wood filler, electrical test tools, etc.
A shop also needs a supply of nuts, bolts, screws, wire connectors, etc. These I carry in a couple boxes designed for the purpose. Black & Decker makes an excellent compartmentalized box that is thin (about 1.5 inches) and broad. It slips neatly behind or along side of other things in the bays or behind a sofa or back of a closet. The B&D parts box is the only one I have found that actually closes tight enough to keep the small parts from jumping from one partition to another, even when standing on end or upside down. I also have a standard small parts drawer cabinet for miscellaneous stuff like valve caps, CATV connectors, an assortment of wire ends, etc. It's a just a small one and I'm thinking of replacing it with another B&D box.
Perhaps this sounds like a lot, but it doesn't take up much space or even add a whole lot of weight. Maybe 45# total? I get kidded about having a traveling hardware store, but compared to many RVers I'm not carrying all that much. Still, I can fix most routine things without heading to a store.
One tool I like is a combination clamp bar and vise. It's a typical lever-operated bar clamp mounted on a swivel base. The base has a screw clamp for attaching to a picnic table. This is my portable vise and the bar clamp also removes for separate use. It is mostly plastic but quite sturdy. It is made by Wilton and called the Multigrip. I think I got it at Lowes.