there is "Good Practise" for everything.
The first thing I look at when seeing a sailing boat docking
or when visiting a marina is watch if they have any signs of "SSB-on-board".
Countless boats do have insulated backstays
; sometimes the lower insulator quite high up, and then run a wire yes or no extra insulated in a hose, strapped along the lower end of the backstay.
As mentioned above, the lower part of this type of end fed wire antenna is high voltage.
You do not want to run it that close another conductor labeit insulated or not.
Look at it this way N°1: neat nylon or other plastic standoffs will give it a real "professional" look
Look at it this way N°2: is it a problem to sail your boat with badly trimmed sails
? It will still move.....is it a problem to hose down your boat or fill your water tanks
with the water
hose jammed or teh water flow severely restricted? No you will be able to hose it but rather slowly...
Look at it this way N°3: will you install your marine VHF
antenna on deck
level if you can install it in the masttop providing you have a good quality low(er)-loss coax? Nope....Will you be able to transmit on marine VHF
with your antenna on deck level? yes for sure....how far?
Well good practise (which is of course backed by science & physics) mandates using stand-offs and also leading the bottom wire to the antenna tuner in the best practise way....that bottom wire is also part of your antenna. It is the choice between the best option and a less-than-optimal installation