Both RTGs, and ny kind of reactor is not realistic by far.
RTGs, while light and not having many moving parts, are not radiologically safe to be around. Unless you understand "being around" as deploying it and having a no-go zone 200 meters wide around it, until it stops working by itself. While it is somewhat-useable on an unmanned space probe, or an automatic weather station in a polar area, its not feasible for any real use with people around.
Reactors are a step above that. They need heavy shielding around them (the pressure vessel alone will NOT cut it enough), they need support infrastructure (turbines, steam dehumidifiers, 2 or 3 (VERY) high pressure coolant loops (of which first one is deadly to be around just like that, due to radiological hazard, and they need large amounts of water (all nuclear plants, sans literally ONE, in the worlds, have either a river, lake, or similar water source nearby).
Furthermore, fuel. You cant just put a natural uranium ore or unenriched natural uranium into an RTG or reactor. Reactor grade fuel means 3-5% enrichment (you need an enrichment plant for that). This is the easy fuel. RTG's do not work on uranium - they use plutonium (highly purified, too! RTG plutonium fuel pellets relase realy obscene amounts of heat due to its high isotope purity and high activity), which is not found in nature unles you breed it (for which process, in turn, you need a specialised breeder reactor, and enrichment plant). All of which are high level of complexity, highly dangerous (radiation, chemicals used) heavy industries.