Regarding stripping, I can only talk about the chemical methods of doing so. I'm not very familiar with silica / sand blasting, so I'll let someone else answer that.
You didn't mention having a shop do it, so I'm assuming you are wanting to do this yourself, so this is fairly long, detailed reply.
As far as acid stripping goes, most rubbers, plastics and polymers are considered to be mostly chemically inert. That is to say, they don't react with most other chemicals very easily. In fact, many of those chemicals I mentioned, such as plastic, are actually more inert than glass. Hydrochloric acid, especially, does not react with hydrocarbons like petrol, tar, oil, etc. Since most plastics, rubbers and polymers are hydrocarbon based... you get the idea... it won't generally react.
Labs use plastic containers with rubber, plastic or silicone seals for highly corrosive chemicals, such as hydrofluoric acid, which can dissolve glass. There are exceptions, but as a general rule silicone is not dissolved by hydrochloric acid
. Hydrochloric acid is also the only acid you would want to use for this. Do not use sulfuric or nitric acid.
You may hear it called muriatic acid, this is the same as hydrochloric. Muriatic acid usually comes between 30-40% hydrochloric acid mixed with water. That is more than enough; anything stronger is much to dangerous to use for what you need unless you dilute it. I use hydrochloric acid quite a lot (weekly and sometimes daily) for paint stripping, for cleaning dirty aquariums (which were sealed with silicone), in the lab, and for removing chrome plating. It's quite useful.
To be safe, my advice to you would be to buy a small container muriatic acid and do a spot test on the silicone/rubber. Pour a small amount of the acid into a glass container and use a small dropper and apply it to the silicone. Let it sit for up to 24 hours and check on it again for any degradation of the silicone. It is unlikely, but the 'silicone' may be another similar sealant which looks like silicone, but is not as inert as silicone. It is best to test before you start.
You may want to try diluting the acid because you may be OK with using just 15%-20% acid. I would test this by diluting it 50/50 and see if it works just as well or nearly as well as the regular concentration. If it does, your acid will last twice as long and save you some money, which is always a plus
There is one thing you need to know if you are going to dilute this yourself: Do NOT add water to acid.
You always add acid to water. In other words, if you wanted to mix 500mL of water and 500mL of acid (1:1 ratio), you would pour the acid into the water. If you do the reverse and pour water into acid, you risk having it instantly boil up and splash up into your face, hands etc. Just think "Add Acid." Make sure you use a glass or plastic container when mixing. You should use, at a minimum, rubber gloves (dish gloves should be fine) and splash resistant goggles and work outdoors. It won't instantly melt your skin off or anything, but you don't want to get it in your eyes, nose or leave it on the skin very long without cleansing with water. It would be wise to use a mask for your nose and mouth, similar to what you use when painting. It may seem like overkill, but it can cause quite a lot of damage.
Here is the Material Safety Data Sheet for hydrochloric acid so you know a bit about it and how to handle it: http://www.jtbaker.com/msds/englishhtml/h3880.htm
If you do choose to strip with chemicals, just do not use acetone. Acetone does absolutely dissolve silicone along with most other plastics and rubbers.
Cheers and good luck,