Dinghy suggestions please

I am an experienced dinghy & windsurfer sailer with 30+ years experience of instructing, mainly in windsurfers, Wayfarers, Toppers, Picos and the like. I retired before the modern generation of fast dinghies were around so little experience there but from racing windsurfers in the past, I do know all about planing and handling strong winds.

Grandson is now getting into sailing and we have bought him a Topper. I want to be able to go out sailing with him, initially 2 up so I can be happy he knows the basics and then be saiing close to him while he is in his own boat.

I consider myself pretty fit & agile for my age (67), weight is about 90kg (ideally could be a bit less!)

So, requirements are for a boat that:

1. Can be sailed helm & crew but can then also be sailed singlehanded (I have sailed Wayfarers single handed in the past)

2. Must have good turn of speed to have a bit of fun out on the water which is why I have been attracted to the new generation of fast planing dinghies ( bit like windsurfing sititing down)

3. Must be capable of being launched/landed single handed easily on a beach

4. Must be either GRP or plastic - no wood anywhere!!

5. Doesn't break the bank, lets say £1500ish max but that must include a road trailer

Have gone round in circles with this, ranging from a Laser 1, Laser 2, Laser Vago, Topper Sport 15, Topper Topaz variant, RS boats etc etc . Also considered boats like the Wanderer but too heavy for point 3 above.

I realise that no one boat meets all these requirements exactly but I am looking for the best compromise.  Any suggestions welcomed