I own 7 Cheji bibs, 2 skinsuits and 2 jerseys (one short sleeve, one long sleeve). 

I am 184cm 80kg 95cm chest, everything I own is L and they all fit me well, with a race fit.

The jerseys and a couple of the bibs I own are no longer available from the Cheji Offical store.

The skinsuit and my favourite Cheji bibs (4 of  the same model  https://www.aliexpress.com/item/1005001939822272.html ) have the red pad and it works for me. I have no issues riding 40km, doing a 20km TT and riding home 40km in the skinsuit (also do similar distances in those bibs).
 
The pockets in the skinsuit and jerseys are in the right position for me (and i do have minor shoulder mobility issues).

The bibs with the green pad don't work for me, and I limit my rides to less than 2 hours. Note these bibs https://www.aliexpress.com/item/1005002191228440.html the leg gripper is just doubled over lycra, so not recommended.

Warning the prices at the Cheji Offical store, I found vary dramatically, I seen my favourite bibs priced anywhere from 35AUD to over 80AUD over a few weeks.

enter

I own both a Garmin Varia RTL510 and Magene L508 with current firmware.

I bought the Varia first, had a minor issue with the micro USB cover bouncing loose on a gravel ride and it had to go back to Garmin for warranty (to replace the cover). I bought the Magene as a temporary replacement as I feel much safer riding with a radar on the rural roads around here with radar.

I have had one false negative from both the Magene and the Garmin in about a thousand hours of riding.  In both cases I could blame how I mounted the radar on that one bike, below a seat roll, without a full unobstructed view.

False positives are common from both units and they occur when vehicles pass in the opposite direction (about 1 in 100), they are very brief.

Differences
The Garmin has micro USB port and will hold the signal of a vehicle that approaches you and then matches your speed for a few seconds longer than the Magene
The Magene is USB C, has a spot for a lanyard and acts as a smart tail light aka brake light. You decelerate it goes brighter.

I have lent the Garmin to three friends I ride with and they have all bought the Magene, after being convinced of the need of a radar and all are satisfied with the Magene.

Never fully tested battery life, my max ride is usual 6 hours and I recharge my devices after that.

How's the magene in group rides? Does it go crazy?

No, it will pick up bicycles as vehicles and if a bike is approaching  with a speed differential (best guess is 8kph or so)  it will issue an alert. So it is quiet during a bunch ride. However, I do use it during races on closed circuits with the light turned  off. It will give me an alert if I am riding on (or close to) the front and somebody is launching an attack from the back.

To sum it all up: Does anyone of you know a rim brake frame that accomodates 28mm tires?
(even better when it has threaded BB, endurance geometry, round seatpost, common headset measurements [eg IS42/28.6 | IS52/40], but that's for another time)

2017 Giant Propel SL fits  28mm tyres (well Conti GP5000 TR S on 23mm internal width rims) just, thanks to its mini V brakes. But fails on every other requirement.

All my other frames an I have a few, don't fit 28mm tyres (GP4000s on  17mm internal rims), and the most common issue is rubbing against the brakes. The one exception is a 2008 KHS flite800 which is made from Reynolds 853 steel and fits all your requirements.

What I am trying to say, is look careful on the second hand market, you might find something suitable. Be it a 2017 Gaint Defy (you might need to check tyre clearance) or a mid 2000s high end steel frame. Rim brake frames/bikes are cheap and plentiful on the second hand market.

Something like these g8 knockoffs ( they don't come in my size    )
https://www.aliexpress.com/item/1005005790948377.html

What size are you?

The "size 39" insoles are really size 46 (best guest look like they are based on large sized G8) and you  trim down to  your  size.

I cut my ones down to size 42.5

The photo of the “thick silica gel pad” is a EI pad, I’m hoping it’s legit

The only review on AliExpress of CGBIG skin/trisuits is one star no comment https://www.aliexpress.com/item/1005006244804848.html

I would wait for a few more sales and reviews

ps as a lot of the photos used in that store are not their own, ie taken from other websites or sellers, I would be suspicious about it having a EI pad

looking for a saddle bag, for small tools and tube, anything to recommend?

I prefer a saddle roll, for example
https://www.aliexpress.us/item/1005005037834823.html
there are plenty of others

been using two of them (tubed and tubeless have there own rolls) for 3 years