I only once had a shot on a 315R and thought that, as a trials bike, it would have made a great enduro bike, but then I ride in the traditional style.
A 200 Beta makes an excellent machine to start on (or for anyone come to that) as it has the power of an “old fashioned” 250 making it easy to ride but still fast across the moors for those real trials. Can’t say I have found mine to be fragile over seven years of use.
If you are going to park it as you suggest then just save the effort and leave the £1500 in a poly bag on your garden gate, there will be about as much chance of it still being there in the morning such is the way of things nowadays. Clever use of polythene sheet should allow “safe” passage to the rear of the house if you have a back door.