I think that this arrangement would be a “for hire” activity under part 135. This type of activity is under close scrutiny by the FAA and your offer is now public. Suggest you only split the gas cost to keep this legal.
The criteria that makes this is a problem is your request to a specific destination for your personal interest, and your reimbursement for more than half the fuel cost.
Hph 304CZ sold
RV6 built and sold
N199EC RV6A flying
Retired Aerospace Engineer and A&P/IA