Expectations among the Lions hierarchy are strong and more than 20,000 supporters are expected to sign up for tour packages and inject more than $135 million into the New Zealand economy.
Interviews for the head coach's role will be completed next month. Eddie Jones has withdrawn from the contest, which leaves Kiwis Warren Gatland, Joe Schmidt and Vern Cotter as the front-runners.
"Yes, and there is nothing wrong with that," Spencer said.
"We have an open book but my view is that coaches have to perform, just as players have to, to be selected, and the greatest test for them is to play in the Southern Hemisphere away from home.
"That's the sharp end of international rugby."
A committee of Spencer, Andy Irvine, Gareth Davies and Tom Grace, with some input from Lions chief executive John Feehan, will select the coach, with an announcement expected some time in September.
Gatland's success with the Lions in Australia in 2013 will give him a useful start when that decision is made.
Spencer said that the nationality of prospective coaches was irrelevant as long as they "got the concept of the Lions" and all its accompanying ethos, history and spirit. The coach also had to be the best person for the job.
Spencer acknowledged there were mistakes on the last Lions tour of New Zealand in 2005, when Clive Woodward's tourists were beaten 3-0 and lost some of the respect the Lions had created on previous expeditions.
"I think that tour abandoned some of the Lions traditions which they thought were not dramatically important," Spencer said. "We have changed those over the last couple of tours for the better."
Things like players sharing rooms, not having a definite midweek side, not leapfrogging venues and giving everyone a chance of a first test start - they are all part of next year's plan.
The 2005 failures went to core values of leadership and teamwork, while there were personality clashes on that tour which did not help.
The Lions want to engage with local schools and communities and do those things with a touch of old-school rugby romance about them.
Spencer is a 68-year-old solicitor who toured with Carwyn James' successful Lions side in 1971 and played 10 games without dislodging test centres Mike Gibson and John Dawes.
He thinks 36-38 players will be picked next year with some initial complications because club finals are played in Europe the week before the Lions' first match against a provincial XV in Whangarei.
There will be no drip-feed arrivals. The Lions will travel as one group, although it is unlikely any players involved in European finals will also play in Whangarei.
"Then it will be no-holds barred," said Spencer. "The coaches don't want soft matches.
"They want to be challenging the players the whole time. They don't like you off your guard for much."
