Bummer
those are not the bolts you want to strip. Because of their location the work area is tight.
DO NOT use a bolt extractor. They are very brittle because of their harness. If you break one off in the bolt it will make other solutions impossible or much more difficult.
Normally when I round off a M6 (5mm allen) bolt my go to is to hammer a Torx T30 socket in, it's slightly larger at 5.5mm. Once seated more often than not I can get the bolt free.
The impact from the hammer strikes can also help shock the threads free.
Looks like a T40 is 6.6mm so that should work, only question is do you have enough working area to swing a hammer to seat the socket? Might want to pull the rear wheel to get more space.
Because the bolts are recessed in the passenger peg brackets it can be hard to get penetrating oil to the threads. If you pop the seat and remove the black fan shroud (careful of the connector) you should be able to see the threaded bosses welded to the subframe that the bolts are threaded into, quick squirt of lube here might help.
If you know someone that is a talented welder or have a fabrication shop in your area the next suggestion is to have them weld another bolt or a nut to the head of the stripped bolt. DC TIG welding allows you to weld steel to steel in close proximity to aluminum. Once things cool down the old and new parts should be one and a quick turn of a wrench should be all it takes. Also the heat from the welding should help loosen the bolt. Just make sure the grounding clamp has a good connection and is located close to the weld area.
If welding is not an option my next step would be drilling off the head of the bolt. The hardware is stainless steel so you need to use quality HSS drill bits. Also make sure you use cutting fluid because, if you overhead the bolt you will work harden the metal making drilling excessively difficult. If you have a center punch use it to create an indent in the middle of the bolt head. Start with a small (pilot) drill bit 1/8", once you have a hole ~ 1/2 inch below the face of the bolt switch to a 1/4" or 7mm drill bit and enlarge the hole. Last step is to use a 11/32" or 8.5mm bit to separate the bolt head from the threads. Once the bolt head is removed the pressure between the threads should be released, most of the time you can use a pick to just turn the remaining part of the bolt out of the hole. If it does not come out freely this is where I would use a extractor, I am a fan of the Pro Grabit's made by Alden.
