20amp circuit with 130 feet 10awg main line and 12awg from junction box to outlets
You'll be fine here
With your pressure-washer load on a 130' run of 10AWG copper, you're a bit over 3% voltage drop, and the LEDs will draw next to nothing atop that.  So, I wouldn't worry too hard about your plans.  What you make the splices in your &quot;junction box&quot; with depends on if you're dealing with an aboveground box or an underground handhole, though.  For the former, you can use standard wirenuts or lever-lock type connectors; however, for the latter, you'll want to use connectors rated for direct burial, as handholes get quite wet inside.