I think it was Bill Bryson used the same technique.
His partner complained that heād gone out to buy a sack of potatoes and came back with two, etc.
His response was, āI hope she likes the two CD players Iāve bought her for Christmas!ā
which will make life a bit awkward should you lose it or get it pinchedā¦
I have copies at home.
What the hell is wrong with asking whether it is un or une?
Take copies out with you, leave originals at home.
Like you, Paul, I dread to be put out of my misery here, and I think the joke is well and truly on us. Cue lots of folk pressing their knees together to stop themselves wetting their pants with another paroxysm of the giggles at our expense. āDeux baguettesā¦ā 
I rarely go out with anything now apart from my phoneā¦copies of car papers are in the car, and if Iām going to shop then Iāll have a bank card or cash. But thatās usually it. I have a photo of identity document on my phone, and medical info is on the lock screen. What else do I need?
Oh, and if the dog is left at home we have a āhome aloneā card for him in case we are in an accident.
I stick my thumb up (one) and (mumble) un/une (loudly) baguette sāil vous plaĆ®t ā¦ monsieur/madame (as appropriate)ā¦
It had taken me a while to realize that āoneāā¦ is shown by the thumb and not the forefingerā¦ but once that lesson was stuck in my mindā¦ it works for everythingā¦ one coffee, one teaā¦ oneā¦ whateverā¦ 
Useful info.
Thereās a scene in Inglourious Basterds where an American soldier posing as a German is given away because he holds up index, 2nd & 3rd fingers to signify āthreeā rather than thumb, index and 2nd finger.
It works well because the thumb is visible (1) and the word cafĆ©, thĆ©, biĆØreā¦ or whatever is clearly heardā¦ itās just the un/une I mumbleā¦ 
Iām forever forgetting, or just getting in a tiz - is it une Margherita given that pizza is feminine, or does Margherita have its own gender?
Also baguette isnāt used much per-se in the boulangeries that I visit - people will tend to ask for āune traditionā, which is easy because tradition is a noun and it is feminine (as is baguette) - but is it un or une āordinaireā, ordinaire can be an adjective so is it āuneā bcause baguette is feminine or is it un because ordinaire as a noun is masculine? 
My aim is to get my French to the point I can have a decent conversation (Iām slowly getting there) but I doubt I will ever get more than a few percent of all the subtleties.
I prattle to mask any inadequacies ā¦ so I would sayā¦
(thumb-up) uā¦ pizzaā¦ margherita/royale ā¦ (whatever) svpā¦
Our baker has about 50 varieties of breadā¦
I donāt worry about. As soon as I open my mouth, they know Iām English and cut an enormous amount of slack. Iāve always found the French very accommodating as long as one tries to speak French (I first visited in the sixties, and several times since). And getting the gender wrong is infinitely better than shouting in English in the hope theyāll understand! (Iāve found the French raise the voice when speaking to me, too, so itās not just an English trait).
Of course, I know a lot of the genders now as I live here and, if going into an unfamiliar situation, my trusty dictionary comes out.
Iāve found that, of all the friendly corrections I garner on my steep climb to something like basic proficiency, the āun/uneā issue is by far the commonest. My āBecherās Brookā stumble-horror is always the pronunciation of āailā which always seems too feeble an utterance to represent the pungency of garlic, and can get confused in my mind with aile (wing).
Listening to cookery programmes has helped a bit.
La pizza
Margherita is a womanās name, so feminine, obv
Margarita the cocktail is also feminine for the same reason
Marguerite the daisy ditto ditto
No confusion possible 
Have you thought about epicene nouns yet? I donāt mean homonyms which are different genders and mean different things eg la tour/le tour but nouns which are both, and then there are 3 which are masculine when they are singular and feminine when they are plural.
Absolutely, and I do try in French (though never quite sure what the etiquette is when the reply is in English).
Wonderful language 
But frequently too confusing for my small brain.
Iāve started to say āJe prĆ©fĆØre te parler en franƧais, si Ƨa te vaā. Itās rather informal but at my age (82 on Thursday) no-one has seemed put out, so far.
Fine, as long as you are speaking to someone you can tu-toi. I wouldnāt do that in a conversation with the garage mechanicā¦
I agree the situation has to be judged carefully, and respect is due to a personās self image and self- esteem, especially on first acquaintance.
But foreigner or not, I think my life experience equips me and entitles me to judge the appropriateness of my mode of address to others, especially as I would never set out deliberately to wound anotherās sense of worth, and have never knowingly done so.
Although Iāve irritated a few on SFN at times. You canāt please everyone always.