Sales Tax / registration - PA w/trade in

in PA we have to pay sales tax (6%) to register a car.

Tesla tells me that they can't do this for me, in KOP, in PA.

I'd get a NJ temp tag / plate. Then I register w/PA and PennDOT.

However, in PA, you pay sales tax on the sale price MINUS trade in.

So, can I still offset 6% of say a $25,000 trade in value vehicle?

I know it's only $1,500, but every bit helps when I'm stretching my budget here...

Thanks

I'd be trading in my 2012 Jeep Wrangler 'somewhere' because I guess they use AutoTrader...?

and picking up my Tesla in King Of Prussia, in PA, but with NJ tags.

Also, I'm waiting for the X, but I assume this applies to any Tesla.