The zx7r has gone, but that would have been a good option for you.
If it was me in your shoes, I would look for a steel framed CBR600 or something like a GSXR600/750 SRAD. They’re great bikes, you’ll be able to buy one ready converted, with wets on wheels and some spares for your budget. There are still loads of spares out there for them, which are cheap and easy to get hold of.
Have a look on motoforum.net as there will be loads of options on there, failing that, plenty of them come up on ebay, so finding one shouldn’t be an issue.
You could go for an SV650, but as you’re a healthy size, having 68bhp might not give you the buzz you’re looking for. The SV also uses the 160 rear tyre, so scrubs aren’t as readily available.
In regards to trailers, it might be worth taking a look at item number 300708016238 on ebay, as they’re certainly an option worth looking at. The only thing with those, is that you’d probably want to have a spare rear wheel with a rock hard tyre on for when you’re towing it! But they’re certainly a lot easier to store. If you spend a little more money, you could get a foldable trailer.
If you want any help at all, then just give me a shout, I have a few months off now, so am about to help with stuff like this. But I guess for you, you need to get these track days out of the way, then if you’re hooked (which you probably will be), then you’ll need a towbar and trailer sorted first I guess.
In regards to getting a track bike, they are an excellent idea at the budget you’ll be spending, even if you have a low side on your bike at 40mph+, you’ll probably do 1500 quids worth of damage, and then you’re bike is off the road for x number of weeks.
Good luck,
Rich