Yes at full power she would use more than i could aford.
I use the 250gr/hp rough formula, so at 300 hp its 75 liters (19 gal) an hour an at 375 hp its 94 liters (23 gal) an hour.
With an classic
under body at 7 kts her wake is minimal so based on the 1 gallon for every 20 hp im using 110 hp to go 7 kts.
With the gr/hp calculation 88 hp for 7 kts.
From the old graphs in the engine
log book it seems she used up to 24 gal/h when towing, but she is long retired now.