Is it possible that your relay can be online for those 22-25 days straight and then hibernate for the rest of the month instead, or must it be the case of every few days? If it could be online for that period as a single block that would be far better.
Also you are correct on the physical safety of the device, which is why running it at home or in a secure environment (ie a good datacenter) is the best approach. However, physical and even server security isn't the threat to anonymity, the intelligence agencies can gather almost as much information from tapping the backbone cables and IXP's as they would running their own or hijacking yours. Generally datacenters are recommended rather than running it at home as it is usually cheaper, lower risk of your door being busted down (of which I have experience in being the target of raids) and it more stable.
I would not at all recommend you use a VPN to route your relay traffic through as this merely passes the burden onto somebody else who may not be entirely comfortable with you doing this without asking in advance. Furthermore, it offers no more security to the circuits your relay is a part of and I would argue it could actually hurt anonymity since you are giving a third party access to the traffic information of your server.
Also, Tor Project only really recommends bridges be run in the Amazon cloud due to the small deployment and low cost, with the IP included in that and for bridges the IP is the real resource as opposed to disk space, bandwidth or CPU power. Therefore it enables lots of new bridges to be brought online easily, cheaply and without the complications or additional considerations that would be required in bringing online an exit relay for example.
-T
Hi, i might have explained the scenario a bit poorly. The machine doesn't go offline every few days but every few weeks, and then for a few days at a time. Nothing to be done about that.
Busting down doors is pretty much spot on about the reason i am unwilling to run the relay on my own IP address: i've read enough news about overzealous law enforcement in my country (non-Tor related, but still), and i'm certainly not going to face the public harassment and general fuss of an unnecessary and very embarrassing seizure.
Regarding the VPN provider's consent - i have asked for permission and they fully endorse running a Tor relay through their services, which means they are ready and willing to handle any and all abuse issues. I'm not sure about the anonymity side of things, which is exactly why i came here asking for opinions, experiences and general advice. All input is very much appreciated.
In the end, in my case, it comes down to either contributing a VPN-tunneled machine for ~25 days a month to the Tor network, or keeping it away from it. If the VPN part is too compromising i'll have to put the thought on hold, but i'll keep on reading in the meantime.