your questions and concerns are not silly.
i carry a phone , compression bandage and an EPIRB locating beacon.
As you say , walking back to your car spreads the venom and you could die within 45 minutes to 2 hours compared to 5 - 7 hours if you use a compression bandage and sit down while deliberately slowing down your metabolism.
If you can summon help with phone or EPRIB / PLB then its smartest to sit down and wait for help to arrive and carry you out , you slow down your metabolism by closing your eyes and listening to your breath passing in and out of your lungs , thats a survival technique taught by yogis and some specialty armed services to assist with survival from gunshot wounds while being transported to medical help , it does relax your whole body and slows your blood and lymphatic circulation , i have used it to slow my heart rate down to 16 beats per minute and breathe rate to 4.5 breaths per minute under a medically supervised environment , but i practiced yoga for years , i do not recommend you try to emulate that !
The compression bandages to use are Setopress or Sports Wrap by a company called HyHealth.
I have seen snakes in rivers many times , they love to eat tadpoles , frogs , shrimp etc so its a valid concern.
When considering snake bite protection keep in mind that snakes see infrared , that is they can see the uncovered flesh and are likely to strike above boots if they can reach it , many snakes will decide to bite you but manouvre behind you to strike from your blind side on the back of your legs.
I didnt see trousers made from gortex yet but i am sure they will be produced one day to a snake proof standard.
If all the above freaks you out a bit consider that most strikes occur when people are trying to kill a snake , some people think snakes are so sensitive they can feel fear or aggression and will strike if they feel threatened or cornered so if you see one , back away slowly while reciting comedy routines ( kidding )
Gumboots are better than nothing but many species of snake can bite through them AND leather , there are many snakeproof boots available from the USA but when i researched it years ago Aussie boot manufacturers told me "there is no market in australia for snake proof boots" because they apparently think we dont have snakes here and they want to corner the market on being Fwits.
Most snakes will buggger off when they feel you approaching except for death adders which will sit still and ping you as you pass , they have the fastest strike of any snake in the world , Tigers and Taipans are aggressive and have been known to chase after humans for 20 - 30 metres when they are hungry or in breeding season much like humans who can also be agro until they have had some jiggy jig , for that reason i carry a blow up snake from the adult snake shop which i throw at the snake to distract it from biting me (not).