Polyester/polythene tents smell, and partner is smell sensitive. How best to treat before long term storage?

Question

I have 2 tents - an Outwell Kansas 5, and a Eurohike Tamar 2. Both need to go in the garage for long term storage for about 2 years, because we won't be able to go camping for a while.

The garage isn't great - its external, unheated, the concrete walls let moisture in, and the air is cold and feels somewhat damp as a result in winter. But not actually mold ridden or damp on the floor, no condensation, even our books in long term storage stay in decent condition there, and they will be off the floor on racked shelving.

I aired both tents indoors over the summer, let them dry, and packed them, but before stowing them last week, my partner told me both bags still smell, maybe of mold but unsure. Nothing was visible when I packed them during the summer. I have a very poor sense of smell, so I can't verify, and I know polyester/polythene aren't nutritional to molds. But I trust my partner's comment. In any case they are very smell-sensitive and if its enough to matter to them, it needs to go before we use them again, anyhow.

Tent fabrics

Research says that both inners are both polyester/polythene. The flysheets are one nylon, the other proprietary "Outtex 3000",apparently some kind of PU-coated nylon??

The plan

1. Wash the tents in something that will kill anything on them, remove any smell on them, but not damage the fabrics.
2. Hang up to air dry indoors.
3. Wash again in some high quality breathable waterproofer solution.
4. Hang up to dry thoroughly again.
5. Show away in bags.

My questions about this process

1. What are some appropriate types of products to both kill anything that is present, and also remove smell regardless? I gather bleash isn't relevant, but I don't know what is useful. I have a spray bottle of Tetrion "fast acting mold&mildew remover" labeled as a pesticide (so I know it isn't just a simple whitener) if that helps, which I used for the shower. (Also if this needs 2 wash-and-dry cycles because mold-icide and smell are 2 separate specialist products, that's absolutely fine, I'm after certainty, or as near as it gets)
2. The tents are big (5 person + 2 person). Pros and cons of swishing them around in a bathtub, or throwing on a gentle wash in a washing machine? It's a many times folded waterproof fabric, so will the products even get to all of it?
3. After the wash, whether tub or machine, is drip-drying sufficient to remove any mold/smell product? Or should I drip dry then rinse again? Same reason - its a many times folded waterproof fabric, so its likely that it'll come out of the wash without the final rinse/swish removing everything.
4. How do I best choose a really good long-lasting effective hard-wearing breathable waterproof soaker?

Other information

• I'm in the UK, so if product names rather than contents/type are mentioned, UK available ones are better.
• No allergies, good gauntlets available, pet cat can be kept far away, and not worried about getting any products on bare skin.
• Commercial, industrial, and more robust product types are just fine, provided when rinsed the tents are human-safe for breathing. I don't need nice and gentle, or mild high street treatments, if there's better

Answer 1

My old tent had what seemed to be a permanent smell, despite airing. I noticed recently that while still waterproof (except for a bit of failing seam tape) it wasn't as water-repellent so I needed to treat it with wash-in proofer. First though, I wanted to get it clean. For that I used Sainsburys delicates liquid but only because I couldn't get Nikwax Tech Wash within my window of opportunity to sort the tent out.

I started with a thorough rinse, in the machine, then took the tent out, put it back in again (to rearrange it and check it was wet all over). Then I washed it with the detergent. I reduced the dose and gave it an extra rinse as it wasn't the proper stuff. While still damp I reproofed it. It no longer smells of old tent. While drying from the reproofing it had an unpleasant chemically smell - so do that outside, but leave it airing for another day or two indoors. Rearrange a few times while drip-drying outside.

For someone sensitive to smells, I don't recommend the detergent I used - get the Tech Wash which isn't scented and is better for your kit. You may need to wash the inner and outer tents separately depending on the capacity of your machine.

I suggest using a "hand wash" cycle if the machine has one. This uses more water and more time, with lighter agitation than the everyday cycles.