I'm not electrically minded so bear with me

I want to get a paint sprayer for the fences, and other outdoor stuff. I know that the longer the cord the voltage drops and the device can overheat

I have a longish heavy duty extension cord, it has a light at either end. IF I needed a few extra metres, can I put a normal extension cord first (as the voltage drop will be low) then the heavy duty cord? If this was an option I would monitor the device temp to make sure it wasn't getting any/much warmer, and I would do a 60 second stint then a 60 second break to help mitigate overload. Or  get another heavy duty cord to join to the other one. Or just buy a longer heavy duty cord that meets my distance? 

I also have a corded linetrimmer that I'd like to use on the berm so that would mean, plug the heavy duty cord into the house then the line trimmer that has a built in longish cord

I could get a battery sprayer, but they seem to not last long, Ozito seems an option but reviews seem not great. Plus these wont be regular tasks so no real need to invest high for rare usage

Thanks

(I will do some measuring later today re distance needed)