Can I control the lights with my phone?

Yes it now have upgraded with APP control function！

Could you splice the power wire to add a switch to it without having to add a ground or extra power line

We don't recommend this. You can change your socket to a socket with a switch, then use the switch to turn it on or off.

Extended cab? If so 550 piece if just the 2 seater go 300 it'll work nicely

Hi，search asin：B08BV2QHQT at Amazon， then click “Customize Now” and choose the one you need. It may takes about 3-7 business days arrive you.

Manufacturer	‎Guangzhou Huaxi Lighting Technology Co., Ltd.
Item model number	16W
Product Dimensions	121.92 x 121.92 x 30.48 cm; 2.38 kg
ASIN	B08BZJ17BM